Do any of those cities have good international flight options? I live in Montreal, the the options are very limited compared to Toronto.

I expect Montreal would be completely ruled out because of the language laws, incidentally. Fine for a branch office, unacceptable for a second HQ.

So, I'm not sure you're right about Toronto being a token candidate. I believe it's the best candidate in Canada.

But, moving to Canada is a big choice. So big you'd really want to consider only the top candidate.