Well.. I live in Vancouver and I can say that there is indeed absolutely excellent chinese food here - I actually find the food tastes just as good here as it has on my visits to Hong Kong, Singapore, Malaysia, Brunei, Thailand, etc...
As for a single chinese dish I love... hmmm hard question. What exactly is chinese? My wife's family is ethnic chinese but they're from Brunei, which means a lot of their food is full of Malaysian flavours. Laksa, mee goreng, nasi lemak, beef rendang, kohlo, etc...
Lately I've been on a Taiwanese spicy beef noodle soup kick. It's not super spicy, but supremely flavourful.