Are you looking to spend your weekends to party and enjoy your single time? Are you living in the eastern part of the country? Will you prefer to live and party in Toronto or Montreal? Toronto is the biggest city in Canada, so there are lots of opportunities there. However, since it is too big, you might get tired of getting places and wait in traffic.
Montreal has more of a European look to it, you can enjoy Old Montreal in summer, but be aware that it is going to be closed in Winter. You have to consider the extreme coldness in Montreal. Toronto is cold, and it had the worst winter last year, but you have to remember that Montreal is much colder.
If you like to learn new language and you are interested in French culture, then Montreal is your place to be. Be aware that the accent that Quebecers are talking are not the same as French people in France. It looks like an old dialect to them. But if you are in Canada, it would be a great opportunity to learn another language and culture.
Canada is bi-lingual, meaning that it supports French and English. However, the support is not that great. You can’t even find French signs for streets in Toronto, if you can find they are rare.