well all the medical universities per se are quite good in the CR. If you're asking which school is the best in terms of getting back to the US/Canada, then I would have to say the First Faculty. If it's Europe, then it's either the First or the Second faculty. And the third faculty is usually filled with scandinavians (so if that's where you wanna go, then the 3rd fac. would be your best bet).

I must however point out to you that each faculty is has it's own pros. and cons. The First faculty usually has the highest drop-out rates (due to the difficulty and the number of courses) but if you get through, it's worth every penny you spent on your medical education (there are quite a few successful graduates of the First fac. in the US/Canada)......but you have to be willing to work hard and keep you motivation high at all times...