I guess NYC is seen as 'cooler' partly because of many blockbuster movies and TV series taking place there, many stars have grown up there, etc. It's all about image, actually. Objectively, I don't think either is better than the other.
Everything. London is a really beige/lifeless city (i've been to both) with a rich history but honestly, who cares?
NYC is the social/trade capital of the world, melting pot of different cultures, ethnicities, etc.
When NY sneezes, the whole world catches a cold. No one cares about London = moral of the story
girl...
I actually love both cities, but I find London to be far quirkier and much more charming than NYC.
Although I'm living in London right now, it was never my favo(u)rite city in the world..NYC slayed me very hard when I was there...but yeah, the fact that London is far more a melting pot than NYC and that you can meet every effing nationality in here it's amazing..
All in all, London is very nice and has A LOT to offer..very expensive too..basically it has scandinavian rules with "latino" people inhabitating it..lol
NY still has that American feel, but it's very "unique" as a city.
I still feel like the quality of life is slightly better in London..but I have yet to figure out what city is "made" for me (besides my hometown - Rome).