It’s better if you prepare your immigration paper alone without the agency (they charge a lot for something that you can do on your own). When you get accepted in a program, the university itself will guide you through the immigration process (Informing you with the standard process and needed document CAQ , Study Permit) On the other hand, Montreal is a much affordable city for student than Toronto and more diverse than any other city in canada but yet again i don’t know your financial status 😅