1) Hong Kong, China

Hong Kong is number one on my list for many reasons: Hong Kong has a whopping 43 buildings over 200 metres tall, 30 of which were built in the year 2000 or later!!! It also boasts four of the 15 tallest buildings in the world… that's all in one city! Hong Kong’s skyline shows a large selection of distinct sky-reaching towers, with beautiful night lighting and reflection. This city exemplifies the post-modern skyscraper and skyline. Finally, the mountain backdrop makes this skyline the greatest on the planet!
Metro/Urban Population: 6.9 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

2) Chicago, USA

Chicago is the birthplace of the modern skyscraper. When Chicago built its first steel high-rise in 1885, it was not the tallest structure in the world but the first example of a new form of engineering that would change nearly every city on earth. Chicago has 19 buildings over 200 metres tall (three of which are among the top 20 tallest buildings in the world, including the tallest in North America). Chicago has some of the finest mid-century architecture and examples of modern skyscrapers.
Metro/Urban Population: 8.7 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

3) New York, USA

New York City has one of the densest and most diverse skylines, with a huge collection of buildings and building styles. Thanks to artist's and Hollywood’s obsession with the city, it is also the most easily recognizable skyline in the world. New York City has an amazing collection of 47 buildings that stand over 200 metres - the most in the world! The four tallest buildings in NYC were all built in the early 1930s! Home of the famous, now destroyed World Trade Center Towers, the Empire State building, the Statue of Liberty and the United Nations, New York City is the financial capital of the western world. New York's skyline is probably the most compact and overwhelming collection of architecture from almost any point in the city.
Metro/Urban Population: 21.0 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

4) Shanghai, China

Not to be mistaken for a space station, Shanghai is a real city! China's biggest and most advanced city, Shanghai was said to be the most modern cities at the turn of the 20th century, but lost its glory. It is now quickly regaining its position as one of the biggest economic powerhouses in the world as well as a showcase of modern architecture and a sky reaching array of buildings, that deck the edges of the semi-circular shoreline. In Shanghai you’ll find 28 structures that are over 200 metres tall and two over 400 metres including one that is insanely tall (468m), the Oriental Pearl TV Tower.
Metro/Urban Population: 13.1 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

5) Singapore, Singapore

One of the best (urban) planned and cleanliest metropolitan cities in the world, Singapore looks like an architectural model city come to life. The buildings cannot be higher than 280 metres due to air traffic control restrictions, but that has added a tall (but not too tall) and consistent building height and space pattern that makes this skyline unique: Three buildings are exactly 280 metres tall and 5 others (8 total) stand at just over 200 metres. The buildings are mostly light-coloured and there is a large expanse of greenery dotted around the city core. This South-Eastern city is definitely in a league of its own.
Metro/Urban Population: 3.8 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

6) Tokyo, Japan

Tokyo is the world's most populated city. Its skyline has a number of unique characteristics that set it apart from other big city skylines, among them 15 structures at over 200 metres tall (including the Tokyo Tower which changes colors every night). But because of the density and vast size of the city, every corner appears to have its own skyline. With the height restrictions and the required red lights that flash atop all mid to tall-sized buildings make the city look spectacular at night. Tokyo is filled with neon lighting and unique, contemporary architecture, and like New York City is also often portrayed in movies for its aesthetic and eye-catching cityscapes. Interesting fact: Tokyo houses the world's largest fleet of helicopters to get around town if traffic gets too crazy.
Metro/Urban Population: 32.0 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

7) Toronto, Canada

Toronto is a meeting place, a crossroads of many cultures and ethnicities. Toronto is downtown Canada, the biggest city in the country with a skyline to match. Toronto has 7 structures in its skyline that stand at over 200 metres, including the astonishingly tall 553 metre, CN Tower, which is often referred to as the tallest free-standing structure in the world. The CN Tower possess the world's highest observation deck, making this city's skyline one of the most immediately identifiable.
Metro/Urban Population: 5.5 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

8) Kuala Lumpur, Malaysia

This is probably the most impressive city worldwide that has less than 2 million residents. Marvelous modern buildings reach the sky here, and while the skyline is not too dense, it does allow buildings to soar and stand out. Kuala Lumpur has three of the 25 tallest buildings worldwide, including the tallest twin buildings, the Petronas Towers (which are considered by some to be the second and third tallest overall in the world), as well as the peaking, 420 metre Menara Kuala Lumpur Tower.
Metro/Urban Population: 1.6 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

9) Seattle, USA

Seattle is the commercial, cultural and advanced technology hub of the Northwest USA and a major port city for Pacific and European trade. Home 4 buildings over 200m and the famous 184m Space Needle observation tower, Seattle is surrounded by mountains and water and offers some picture-perfect views. Seattle is commonly referred to as the Emerald City and renowned as a great social and corporate city with great planning. 
Metro/Urban Population: 3.7 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

10) Shenzhen, China

What was a tiny fishing village on the border of Hong Kong in 1970 is now a buzzing metropolis of over six million people! Already containing 18 buildings at over 200 meters tall, including the Shun Hing Square (the 8th tallest building in the world), Shenzen is a spectacle of lights and neo signs after sunset, you can’t help but ask yourself... if you are in a video game or in a real city.
Metro/Urban Population: 7.2 million

This Print is Not Available For Sale

11) Dubai, United Arab Emirates

Is this a mirage in the Middle East? Seemingly out of nowhere emerges a city in the middle of a desert. This is Dubai, a city that produces only the best modern architecture in the world. Already home of the world's tallest all-hotel building and the tallest all-residential building in the world, AND currently proposed to build the world's tallest building, this skyline might just leap to the number 1 spot in the near future. While the skyline is not so dense, each building is a marvel all on its own. As a skyline it probably can't compete with the larger cities, however the individual buildings in this city are by far the greatest examples of modern architectural accomplishments. All seven structures in this city at over 200 metres tall were built in 1999 or later - that's how new this city is.
Metro/Urban Population: 1.5 million

This Print is Not Available For Sale

12) Seoul, South Korea

This city's skyscrapers are divided into many clusters, spread amongst the main businesses and residential districts. Most of the recent growth in Seoul's skyline, however, has been of residential towers over 60 storeys high that are shooting up like blades of grass! There are 10 buildings in Seoul over 200 meters tall and much of the mid-rise to high-rise structures are lined up in a linear fashion, creating a "wall" of buildings like no other. Seoul is where the ancient Eastern world meets the modern West.
Metro/Urban Population: 20.8 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

13) Frankfurt, Germany

Certainly one of Europe's most interesting cities in terms of skylines, Frankfurt is home to five structures that are over 200 metres tall. These modern skyscrapers are marvels compared to those other, mostly non-existent ones scattered across European cities. The contrast here is interesting: The city combines low-rise, high-density traditional European architecture (some of which is over 1,000 years old), with modern towers that stick out like sore thumbs, but are impressive nonetheless.
Metro/Urban Population: 4.1 million (region)

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

14) Sydney, Australia

Australia’s showcase city, Sydney has one of the most recognizable skylines due to its world-famous harbour, often referred to as the most beautiful natural harbour in the world. The Sydney Harbour has many bays and inlets. It is spanned by the monumental Harbour Bridge, and the Opera House sites on the shoreline like a white flower. The Sydney skyline is world-class with hundreds of skyscrapers in the central business district and many more high-rise buildings in the outlying neighbourhoods. Sydney has 8 buildings over 200 metres tall.
Metro/Urban Population: 4.2 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

15) Dallas, USA

The "Big D", is a major inland American city. The city and metropolitan area lies amidst vast, high, and varying rolling prairies - with hundreds of large & small lakes, rivers, creeks, waterways and meanders. But Dallas; downtown is the center of the Forth-Worth-Dallas Metro Region which is home to 5.9 million people. Dallas' skyline is home to 7 buildings over 200 meters and the 187m Reunion Tower which looks like huge sphere of light! The skyline is very distinctive at night as it building lighting is very colorful, particularly with lots of green.
Metro/Urban Population: 5.4 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

HONORABLE MENTIONS

16) Sao Paolo, Brazil

“What building did you say they lived in?” Finding it in the largest mass of condensed apartment buildings anywhere would be like finding a needle in a haystack. Sao Paolo has a population of over 18 million people! While the buildings are not super tall (with only a single structure at over 200 meters tall) this skyline is nevertheless completely and utterly stacked. Sao Paolo has a fleet of over 500 helicopters, the second largest helicopter fleet in the world, because if you want to get around by roads, they are as packed as the dense skyline.
Metro/Urban Population: 18.3 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

17) Guangzhou, China

Guangzhou is a very modern city, yet it is called "the City of Flowers,” as each of its spectacular skyscrapers is surrounded by grand green spaces and flower beds. Although it only has six structures at over 200 metres tall, there are plenty of other high-rises, each displaying a design that stands out in its own respect. This includes the 391 metre, 80-floor, CITIC Plaza which appears transparent against the (usually) clear blue sky!
Metro/Urban Population: 4.1 million

This Print is Not Available For Sale

18) San Francisco, USA

Although SF has a large population in outlying regions, "The City", itself is densely packed into a compact area of a peninsula. This makes it the second densest city in the USA, next to NYC. Another North American skyline with little recent development, but still home to the classic Transamerica Pyramid (an architectural classic) is one of the three 200 towers over 200 metre. The famous golden gate bridge and surrounding water and mountains makes this skyline dazzling from almost any angled it is looked at from.
Metro/Urban Population: 7.7 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

19) Pittsburgh, USA

Although Pittsburgh only has two buildings over 200m tall, its skyline is very impressive nonetheless. Pittsburgh has nicknames like the "city of bridges", "the Burgh" or the "golden triangle" which outlines its true characteristics. It is surround by three rivers and the CBD is shaped in a triangle and surrounded by golden color bridges. The city is also surrounded by hills and valley's giving access to great views of the city. The city has not had a major skyscraper raised since 1988, but good planning and a scenic surrounding region still makes it a great skyline.
Metro/Urban Population: 2.4 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

20) Houston, USA

Everything is bigger in Oil-town Texas!! With 14 post-modern and individualistic skyscrapers over 200 meters, Houston is only beaten by the top 5 cities on this list in that category. Houston is built on a major port, but what is interesting is its lack of zoning restrictions, which has allowed major skyscrapers to be built all over the city in a scattered fashion. In fact, the tallest building in the United States outside a financial district in a major downtown is the Williams tower.
Metro/Urban Population: 5.2 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

21) Atlanta, USA

A reputation as a modern, progressive city that houses many corporate conglomerates. The skyline is truly unique, with 8 structures over 200 meters tall, stretching in a straight line along Peachtree Street. The tallest building in any suburb in America is in the nearby Sandy Springs. In fact Atlanta really has several skylines, which may all be seen together in various combinations from different vantage points. Atlanta maintains its Southern US flare, but continues to grow at a ridicules pace. It is an example of suburban sprawl come wild. Even so, the skyline is nonetheless impressive.
Metro/Urban Population: 5,200,000

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

22) Melbourne, Australia

This diverse, modem and multi-cultural city has many of Australia's tallest buildings, including the new 300m Eureka tower, just one of 8 buildings topping 200m. This city is constantly building new skyscrapers without compromising  the essence of the city and it modern, organized and celebrated. In a sense Melbourne is a newer, smaller Toronto, that is rapidly growing and joining the ranks of an internationally renowned, modern city.
Metro/Urban Population: 3.5 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

23) Rio De Janeiro, Brazil

Its wonderful physical location gives Rio what is arguably the most beautiful setting of any city in the world. This cityscape contains both one natural wonder and one man made wonder of the world. Rio has few skyscrapers, but is very dense and flat and looks like a scatter of buildings in a valley (which it is what it is).  from any of the of the breathtaking angles the city can be view at from the surrounding rolling terrain.
Metro/Urban Population: 11.2 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

24) Johannesburg, South Africa

The "City of Gold". Johannesburg is the largest city in the world not built on or near a major water source. That alone makes it a phenomenon onto itself. The majority of the skyscrapers in the CBD are from the boom of the 70s and 80s. Three towers stand at over 200 meters and are the tallest and most grand structures in all of Africa. The city has promised to rejuvenate its CBD with more buildings, but the fact still remains that the nightlife, shopping and the culture is still very much alive. Because of the geography and topography, the city is also very "planned" in a grid iron fashion, which gives it a unique look.
Metro/Urban Population: 6.2 million

This Print is Not Available For Sale

25) Osaka, Japan

One of the largest cities in the world, both in area and in population. Osaka is home to the famous and unique Umeda Sky Building. The city is a sea of high-rises in a nested maze of canals, spanning bridges, freeways and parks. With 2 buildings over 200 meters and plenty of other futuristic buildings and no real CBD, but rather a continuum of seemingly sporadic development, Osaka's skyline is very unique and interesting.

Metro/Urban Population: 14.3 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

26) Boston, USA

Boston's skyline doesn't particularly stand out as special from a distant glance. However, Boston exhibits a really interesting blend of old and new architecture. The cityscape is highlighted by the distinctive, early twentieth-century buildings and post-modern business towers. The fascinating features of the city include the harbour and with a series of juxtaposed buildings in the east side of the downtown. But the two tallest buildings (the only two over 200 meters) are located several blocks away in the west side of the downtown. The ultra cool bunker hill "bridge" with triangular span cables adds to this skyline from some angles . The city is the oldest American big city, but the most youthful and vibrant, being home to the most colleges and prestigious Universities in the western world.
Metro/Urban Population: 5.6 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

27) Panama City, Panama

Near the Panama Canal - the only connection between the Atlantic and Pacific Oceans, Panama City is without a doubt the most prominent skyline in Central America, Panama is a beautiful city with a shoreline of modern condo and hotel developments along the waterfront. The lovely setting makes this skyline a pleasure to look. Some are dubbing Panama City the "Dubai of Central America" because of their new found openness to allow major development,
Metro/Urban Population: 800,000

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

28) London, England

This Print is Not Available For Sale

London is city with a rich history. If this list was the greatest architectural cities or just the greatest cities,  London would be near the top, without a doubt. However, because of the low-rise, dense structure of the city, it never really had a visible skyline. London bridge and the giant Ferris wheel made up the bulk of the skyline for the last decades. 7 of the tallest 10 structures in London have been built after the year 2000. The city now has a visible CBD and some very interesting sky-reaching architecture, such as the 30 Mary St Axe Tower. There are 3 buildings over 200 metres in London.
Metro/Urban Population: 11.8 million

29) Las Vegas, USA

In a way I wish I didn't have to include Vegas because it defies all the conventional rules of how city's evolves and what a city consists of.  However, where else can you find Paris, London, Rome and the great pyramid in one city? The entertainment capital of the world and America's most visited city, Las Vegas. Where else? This the fastest growing area in the United States and "the strip" offers the most cool pieces of architecture, lighting extravaganza and entertainment simultaneously visible to the human eye. The structure over 200 meters is the Stratosphere, which is 351 meters tall, but Vegas also is home to 10 of the 10 largest hotels on earth!
Metro/Urban Population: 1.7 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

30) Minneapolis / St. Paul, USA

Minneapolis & St. Paul are rightly named the twin cities. Minneapolis has not built a skyscraper since 1990s, however, there is a lot of foresight in design with a lot of creative planning as well. Home to four buildings over 200 meters and designed to have a mountain like shape, this skyline is not one to be overlooked. The city allows for more density and height as your eye move towards the centre of the city, building up the skyline to a climatic peak and then breaking down. Minneapolis sits on the Mississippi River and has lakes plotted all over the city giving many vantage points towards the concentric skyline. This city is also well lit at night, making its cold clear, winter nights one of the friendliest of all. 
Metro/Urban Population: 3.5 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

30) Montreal, Canada

Don't be fooled by this city that only has one building over 200 metres tall. Montreal is a super dense city with European cultural flavour at street level, and corporate North American commerciality in the towers above. Variety, is a word that comes to mind when one thinks of Montreal, which is diverse both in culture and in architecture. The island city is surround by water and has a mountain "Mount Royal", hence the name, looking over the city (which offers a great view). The nightlife and the views in this city are exciting and vibrant to say the least.
Metro/Urban Population: 3.5 million

Buy This Photo in Fine Art 36 x 12 (3 feet wide) for $79.95 (free shipping)

Top 15 Skylines Method

Method to this Madness?
Since skylines are mostly about aesthetic appeal and very subjective, how can I judge which skylines are the best? Well, there are some rigid criteria I've used for this list. So here is what they are in order.

VVII - Visual Vertical Impact Index. This is the most important aspect of a skyline. The city must have a recognizable man-made vertical set-up or design in an urban area, visible against a horizon. The way this score is calculated is: Each skyline is manually scaled using a straight on view (panoramic style photograph) to create a silhouette or man-made mountain. Once the photo is scaled, the ground is given a score of 0 and a score of 20 is given at about the 200 metre mark. Then twenty different points in the skylines silhouette are picked and used to determine to VVII. Although there is some subjectivity to the VVII index, it is a quantitative method. It does not only take into account the height, but the visual impact against a horizon. As you can see in the example below, the median perspective of the height and girth of the skyline plays relevance over strictly height. In the example below, Skyline A has an skyline that literally fills the vertical and horizontal horizon with a mountainous silhouette where as Skyline B can be described more as trolling hill with one major peak (the tall building on the right). 

Overall the VVII of Skyline A (12 VVII) is greater than B (VVII 9). Wikipedia's defines "A skyline is best described as the overall or partial view of a silhouette of a city's tall buildings and structures consisting of many skyscrapers in front of the heaven in the background. It can also be described as the artificial horizon that a city's overall structure creates.". This is why a city such as Rome (a great city indeed) cannot be included in this list as it's VVII would be very low, since the city is barely visible due to lack of height on a horizontal plane.

Height - Total height of the city's structures. Visit the World's Best Skylines by Egbert Gramsbergen and Paul Kazmierczak to get a objective ranking of skylines based on building heights. Also see the ultrapolisproject.com - World's Tallest City Web Page

Density - Not the population, but rather the density of the skyline.

Style/Organization - This is a more subjective area. However, polls and preferences on major architectural sites gives us an indication of this. Polls taken on accredited sites (e.g. Skyscrapercity.com) for personal preference

Feats/Marvels - The number of structures over 200 m and other renowned structures that are within the city are considered in this. City's with record holding structures (such as first building over 100 stories, etc.) will have a higher score in this area. Statistics and facts from emporis.com (the most accredited architectural site) is the predominant source .

Uniqueness - Another subjective area, however, there is a general consensus amongst experts in the field.

Surroundings/Topography - This is the geographic variable, "in front of the heaven in the background" that skylines backdrop stands before. Also a subjective area, however, areas with lovely mountains and bodies of water that compliments the skyline is critical. Additionally geographical representation is in effect here, there is an attempt to represent cities from every continent.