I'm going for NY. Main reasons being I prefer the restaurants (still haven't found a comparable NY steakhouse in London), it is more down to earth, cheaper and 4 high quality sports are readily available to watch live.
I heard that property was more expensive per square metre in New York. Sport is better in London too. Let's not pretend US sports count.Having spent long periods of time in both, no comparison. Everything bigger, better and cheap in New York.
I like New York a lot though.