Well I'm living in Vancouver and working for a large cellphone manufacturer - so I'm probably half qualified to answer.
In the cities and most towns, GSM offers the best coverage. Outside of cities CDMA coverage is probably better but you'll be lucky to get any coverage at all in much of BC (like Oz there's an awful lot of remote nothingness out there).
Generally it's pretty comparable with Australia for coverage - gsm is probably your best bet though.
WCDMA is non-existent, unless you're going to be living within a mile radius of where I work ;-)