I'm in Mississauga and use VIF Internet, which is based in Montréal. They are dirt cheap, provide decent service, and do not impose any bandwidth limits (only a soft cap is imposed starting at 100 GB, which you can read all about on their website -
VIF Internet) so you always pay the same amount no matter how much stuff you download. I also have my VOIP phone through them, and although their phone service can be spotty at times (could be my line though), you get Caller ID with unlimited Canada/U.S. long distance included.
I've been with them continuously since 2007, kept them when I moved to Ontario, the price can't be beat, and I have yet to find a competitor that even comes close in terms of bang for the buck...