I live in London at the moment, and I love it. It has one of the best skylines ever, you've got really magnificent and old buildings like St. Paul's right next to modern buildings like the London Eye, which you just don't get anywhere else.
London
New York City
The New York skyline is very nice, but most of the buildings are relatively recent and so you don't really have as much diversity as you do with London. Even going on the underground is amazing, it is the worlds oldest metro system and some of the stations look amazing
Canary Whart Tube Station
Plus the fact that it is arguably
the capital of the world.