Montreal is awesome. Toronto is more just big city vibe (but still cool). Depends what you enjoy doing
Know nothing about either mate. Just looking for somewhere interesting to go to have a mooch around. Guess I want (bearing in mind I'll likely be on my own), plenty of places to eat without feeling like a cock because I'm on my tod, same with bars/pubs. Plus some interesting stuff to do in the daytime, just for a few hours each day. Won't be looking to run around all day just ticking tourist boxes, just some want interesting stuff to fill a few hours each day to make the trip worthwhile.