London. I like big, dense, multicultural cities with lots to do at any moment of time, lots of different people and high-quality food from as many cultures as possible readily available. On that measure I think the only city that compares (and is probably better) is New York, but I have a citizenship and lots of family + friends in the UK so it's a much more convenient place to be.

I'm working on moving there to do not-remote development at the moment, incidentally.