I live in Burnaby, was working temporarily in Victoria for the past six months, have ridden my bike in Edmonton, Calgary, Hamilton, Toronto, and Montreal. I would say that the worst place for cycling amongst all the Canadian cities I've ridden in has to be Mississauga. Mississauga is designed to be a number of east-west and north-south multi-lane throughfares that create various "islands" of residential areas. So you have a residential area that could be about 8 blocks by 8 blocks, but it is surrounded by 6- or 8-lane major roads with no bike lanes and no special accommodations in the curb lane for other than right turns. Within each island, there are nice, quiet residential roads. But to get from one "island" to another, you have to negotiate these broad throughfares. There is one "bike path" but it doesn't really go anywhere.
I think a lot of the problem has to do with Mississauga's 93-year-old mayor who doesn't appear to have done anything to make cycling viable in this town. Once you're out of Mississauga, even in Port Credit or Etobicoke, things are much better.
The surprising town in southern Ontario is Hamilton. You can actually find nice places to ride in steel town. And of course, west of Hamilton to Niagara appears to be fine for riding.
L.