University Rankings help...?

I'm a grade 11 student debating about taking the SATs and applying to American universities in the fall. I want to know if it's worth it. There are high ranked universities in Canada (McGill, UBC, UofT, Queen's, etc.) that rank higher than some American universities like Notre Dame, NYU, etc. (depending on the ranking, of course) My question is, if a Canadian university like McGill is ranked higher than a university like Notre Dame, is it still worth going to?