Hmmm...you didn't get many responses here, huh?
I think that might be because there is a constant debate over the quality of Thai food in Toronto. I have read many good reviews of Mengrai Thai for dining in, I like Thai Jasmine for delivery, there is a little hole in the wall on Bloor at Spadina (Real Thailand?) that's cheap, cheerful and tasty... Pi Tom is on Alexander just off Yonge. For more formal dining, some people love Golden Thai, though I haven't been as impressed...
I think it depends what area you are looking in and how much you want to spend.