As @phdwanttobe said, it really depends on what your field is and what your career goals are. UBC and UofT are two of the best schools in Canada. In general, I would compare them to some of the best schools in the USA, but the top schools in the USA are often superior to Canada's school. For example, Canada really does not have an equivalent to top private schools such as Harvard, Yale, Stanford, MIT, Caltech, Princeton, etc. These US schools have tons of private donor money. There are no privately funded elite research schools in Canada---they are all publicly funded and often have less resources than the top US schools. So if we were to compare UBC/UofT to US schools in terms of world rankings, for most fields, the top private US schools would take the first 10-20 spots. The Canadian schools would rank along with other large and good US public schools, so I'd put them in the 20s.
In my field though, there are many graduates from UBC and U of T that end up at top private US schools later on. This is true for both undergraduates from Canada going to top grad programs in the USA as well as PhD graduates from Canada doing postdocs in the USA. So I would say that although it may depend on field, in mine, going to U of T isn't going to significantly hold you back from other opportunities in the USA later. And really, it's only worth to compare U of T with the top private US schools when you have offers in hand for both, as the top US schools are also hard to get into.
