carlew
nov is the low season, so most of the airlines are cheaper - I used to fly UA - only 1 stop in chicargo.. but since not sure when is your return flight - so you better check witht the travel agent in HK.
currently is the cheaper is Korean airline - but need to stop in Souel, and SF then to Toronto.
If you are just going to Vancouver, then, JAL or Korea airline is good, only 1 stop