If you're ever in Whitby on a weekday, stop in for a pulled pork, pulled chicken or brisket sandwich at Buster Rhino's. They have a lunch counter operating out of their production facility with limited hours (Mon, Tues 10-3) (Wed, Thur, Fri 10-8) no weekends. They offer cafeteria style seating if you want to eat in. I've never tried their ribs but the last time I checked they offered a Friday special which was a full rack of ribs right from the smoker, a side and a pop for $13 or so (I'll have to double check). It'll be the only place you'll find a consistent BBQ product in the GTA. The BBQ will more than likely be reheated but let me say think you'll find it to be the best you'll find in the GTA.
Pick up a combo with their fries, they are excellent as well. I'm not totally sold on their salads or hushpuppies but that's a matter of personal preference...
Here's a shot of my last brisket sandwich:
Here's a link to their site: