havent done enough travelling to make a definitive list, but just off the top of my head...
1. Toronto - love the neighbourhoods and the local culture! I think Toronto is on the verge of greatness and the next 15 - 20 years will be very exciting. All the infill happening downtown, exciting new architecture, the waterfront reclamation... all heading in the right direction.
2. San Francisco - beautiful architecture, densely built, temperate climate, great location. Contrary to some other negative comments on here, SF is very rebellious and often disregards national directives... example - i.d. cards for illegal immigrants, civic health care program... very progressive. I found the vibe here to be very pleasing and I felt just as comfortable walking the streets there as I do in T.O.
3. Singapore - even with all the government censorship and harsh laws. I love the tropical location, fantastic mix of old and new architecture, immaculately clean streets, world class cuisine. What are the chances of the US invading and repealing the chewing gum laws? The chewing gum industry must be a big lobby in the States, no?
As for London, it was a cool place to visit, but I just found the traffic and crowds and the underground just too stressful. The pace and rush of things there was just too much to feel comfortable living there. Though the megacity scale would offer endless opportunities for exploring....