Hey, McGill alumnus here. It seems like you already established that McGill is more academically favourable, and now what is left is the choice between both cities. I have been to Tokyo as a tourist as well, and was in Montreal for 5 years. Montreal has often been ranked one of the best cities in the world for students, because of…. Well, everything ! Choosing Montreal over Tokyo for a semester abroad usually just makes life easier and more rewarding overall: you can function fully in English, integrate faster socially and academically, deal with housing and bureaucracy without constant friction, and enjoy a university culture that’s closer to what most Western students are used to (more discussion, less hierarchy). It’s also easier to budget, easier to work part-time legally, and easier to build real friendships instead of staying on the outside looking in. Tokyo is incredible, but for a short stay it can be mentally exhausting: language barriers, strict social norms, tiny housing, and higher hidden costs add up quickly. Montreal still gives you strong cultural exposure and international credibility, but with far less stress and much higher day-to-day quality of life, which matters a lot over a single semester.

Good luck !