London? Well, it's a nice quiet place, but I kinda find it a bit slow. And it's a little conservative for my tastes. Mandarin is a big buffet chain, but it is sort of Canadianized Chinese food.
I live in Toronto. It's much more lively here (ie. not as laid back as London). And it has MUCH better Chinese food.

(But if you really like it, Mandarin is here too.

) I believe a couple of surveys in the last few years have concluded that Toronto has the most cultural diversity IN THE WORLD.
The problem in Toronto is that it's so damn big - takes a long time to drive out of town, and the traffic sucks. Plus I think it's the most expensive city in Canada (although it's cheaper than most large US cities).
Montreal is nice - best party town and it has very cool cultural stuff. Outside of downtown though some people don't like English speakers as much. It is a very inexpensive city and the drinking age is 18.
Vancouver is VERY laid back for a big city. Rains a lot in the winter, but it is so close to so much outdoor stuff. It's also expensive though and the traffic also sucks there, although not as bad as Toronto.
Calgary is OK, but although it is a relatively large city, it's has the feel of a smaller city. Fine for some people but as you may have guessed, I prefer metropolitain centres.