All Canadian medical schools are accredited, so it's not as difficult as for internationals.
Hb1 visas are the most sought-after but few programs hand them out because it's a hassle; from my understanding it's only realistic for top and bottom tier students (top tier programs will do whatever it takes if they want you; bottom tier programs will do whatever it takes to fill their spot).
The other visa (J1?) forces you to come back to Canada for at least two years after residency, forbids you to moonlight, etc, so it might conflict with your goals.
Keep in mind, however, that the Canadian government will issue statements to let you do your residency in the USA only in certain fields (lots of primary care), and in limited quantity. I believe recent developments have lowered even further the number and scope of those statements. Might wanna look into that.
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If you do residency in Canada you can practice in the USA (and vice-versa) only if residency length is the same in both country. e.g. Psych is 5 years in Canada and 4 years south of the border, so an American would have to train (as a fellow) for at least 1 more year before being able to practice in Canada, whereas the Canadian could practice immediately in the US.