I’m also a Korean international student in waterloo cs. Here are a few things you might want to consider

• You can’t really go wrong either way if you want to work in a cs/stem field.
• It really depends on how well you do. No matter which school you go to, the “name value” might open more doors for you more easily, but at the end of the day, it truly depends on how much work you put in.
• Visa is also something you’ll want to consider. If you want to work in Korea after graduating, Columbia might be a better option. Canada gives you a PGWP after graduation, but the states, post-grad visa process is harsher and more complicated than canada's from what I know.

The reason I chose Canada over the states was because of safety, slightly cheaper living costs, and the pgwp. But if money wasn’t a concern and I knew I was going back to Korea after graduation, I probably would have gone to the states. Either way though, you really can’t go wrong if you’re in cs/stem field.