Besides for Toronto (which obviously I would live in, as I live there now)...
(1) New York (Manhattan) - I love that you can live some place and walk everywhere and that whatever you want, whenever you want it, it's available.
(2) Hong Kong - only spent 1 day there, but I was IN LOVE. Big, tall shiny buildings...
(3) Santiago, Chile - very cool city, lots of old colonial architecture, mixed with new areas with the tall, shiny buildings that I like. Weather is excellent, both skiing and ocean nearby, and a stable economy. It's like Denver, but bigger, cooler and with less white people wearing fleece.
I've never been to London, but I'm going in August, so I may add it to my list after I return. I think I will like London.