The PC-12 seems to be quite popular in Canada for small airlines. In addition to those mentioned by S'dawg, they're also operated in as charter, scheduled, and private aircraft by Bearskin, Wasaya, RJM, Chartright, Kelner, Pascan, Thunder Air, North American Charters, Ontario Government, Nova Steel, the RCMP, Keewatin Air, Expressair, and Nakina. I also believe there's other carriers planning on using them.
The PC-12 has several advantages. I heard (can someone confirm???) that at 9 seats it only needs one pilot, not 2. And being under 20 seats it doesn't need flight attendants. As a single-engined aircraft, it's cheap to operate. It has a high degree of flexibility because it can get into lots of airports. And although I've never flown one, I understand it has reasonable comfort levels.
The principle disadvantages of the PC-12 are that it doesn't match the appeal of jets, and it's also a fair amount of money to purchase (new aircraft have that tendency).
Personally I like the idea of using PC-12's. Compared to larger aircraft, they're lower risk. But be careful of competitors flying larger aircraft in the event they start up YQB. Flying niche market routes, however, that may not be a problem. I don't think you'd be working with connecting traffic to other carriers, so you could also use convenient alternative airports, such as Toronto Island or possibly even other alternatives to Pearson. There's also Ottawa-Rockcliffe, and Montreal-St.Hubert. I don't think it's wise to fly entirely to secondary airports, but by using some of them it might help reduce landing fees.