It really depends on what is the lifestyle you seek.
Here is what Montréal has to offer: European-style lifestyle with north american commodities. Cheap housing compared to the other big cities in Canada. Great food, awesome nightlife. The economy in my province is not so great however. Taxes in Canada are higher than in the U.S. and Québec is among the highest in Canada. Universal health care, which means that you can go to any hospital at any time to be treated (be ready to wait a long long time at the emergency).
Montréal is on an island so it's constantly humid. The province of Québec is home to 6.5M french-speaking canadians so expect to speak french if you get outside the island of Montreal because 99% of the french-speaking people living outside the island of Montréal speak only french. And no, just because the U.S. is our neighbour does not mean that we absolutely have to learn english. It's certainly to our advantage to do so but you can live your whole life in french.
I spent some time in Toronto and I hated it. I visited Vancouver once and it certainly is a lovely place. The climate there is certainly the mildest in Canada.
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