It depends which university. If you get accepted in an Ivy League university like Princeton or Harvard, of course USA.
If you attend a public state university, University of Toronto, McGill, McMaster and Waterloo are much better.
Security wise, Canada is much safer than USA.
Canada is cheaper, after you take all costs into consideration.
Go to big city, if you go to Boston or New York City, just go. Forget California, which does not have the cultural richness Boston and New York can offer.
If you go to a small city or town in USA, you may as well come to Toronto or Montreal.
In Toronto, there are half a million Chinese. You will get what you want. There are 2 cities in USA with so many Chinese: San Francisco and New York.