Top cable companies in Canada would probably be Rogers, Shaw, Cogeco and Videotron. Might be missing a couple out east or west, but Cogeco is pretty big in a lot of Ontario.
"Established over 40 years ago, COGECO is a diversified communications company. COGECO provides its residential and commercial customers with analog and digital video and audio services, as well as high-speed Internet access. Cogeco Cable is the second largest cable operator in both Ontario and Quebec, and ranks fourth in Canada in terms of the number of basic service customers it serves."
They only operate in Ontario and Quebec, but that is where most of the people are in Canada. Again, being from Vancouver, I've never heard of them until this thread. Ontario and Quebec are huge markets though.