I've lived in LA, SF, Boston, Toronto, and Vancouver.
I liked SF and Boston. Things moved a lot quicker. The cities were more populated, people were more educated (I was near Harvard / MIT / UC Berkeley ) and unassuming.
I went to college near Toronto, and almost all my professors were American. They liked Canada for all the reasons I didn't like it. Things seemed to progress slower than their American counterparts, and people were less wound up. The downside is that the service quality in the private sector is not comparable that of the US.
I currently reside in Vancouver. It's beautiful here, but you get lots of rain during winter seasons. People are friendly. It's expensive if you live near the city, but where isn't?
Pay is definitely not as good if you're an engineer... Maybe 70 cents on the dollar. If you're trying to build a software startup, definitely consider moving your HQ to Canada (or outside of SF!), and keeping a corporate office in SV for fundraising. There's less competition for engineers, and you'll make 30% more progress per dollar invested.
Technology-wise, I'd suggest Waterloo. Silicon Valley hires graduates from U of Waterloo only second to UC Berkeley. Perimeter Institute for Theoretical Physics chaired by Stephen Hawkings is also there. The city is also home to Institute of Quantum Computing, started by the founder of Blackberry.
D-Wave, one of the major players in quantum computing is based in British Columbia.
In terms of AI, Canada is a bit of a talent drain. Most of the lead researchers and professors have been lured to Oxford or Google or wherever.
Venture Capital presence is limited here. Vancouver has only got a handful of major venture firms. Though, I met a couple of investors from Silicon Valley investors trying to start something up near UBC. I can't say much about Toronto.
Quality of living is pretty good here. I can go out for walks during midnight and not have to worry about getting robbed - something I was never able to do in LA. Many parks.
Overall, you'd like Canada if you're willing to trade slower pace, liberal views, colder weather for population size, and American imperialism.
Every American I've met in Canada really enjoyed being here, just as every Canadian in America I've met really enjoyed being there.
I'm no exception. There's something I love about the narrow Cobblestone streets in Cambridge, the golden hills in SF Bay Area, the weather in LA. And oddly enough, I've found that people I've met in the US are more personable than those in Canada. I suppose that comes with the more unified sense of national identity that is in someways a fascade.