In North America I would vote Montreal. It's 1/2 price of most American cities and 2x funner and cooler than almost any of them. LA and NYC have tons of cool, but they are expensive and doing fun stuff is generally expensive. Not so Montreal. Mtl has way more going on than even SF ever had back in the day, and it's much bigger than Austin, Boulder/Colorado Springs etc. etc.. During the summer, Montreal has an unbelievable amount of stuff to do. Carnivals, festivals, just jammed back to back, overlapping one another all summer.

More students per capita than anywhere (depending on how you define 'city' because of course Boston is a big one, but Mtl has 5 Unis right down town within a few Km of each other).

And 1/2 of the city is French, and it's like being in another country.

It has an intellectual/creative tradition from French culture, also, it's actually a global leader in AI, and not just one of those cities making pompous statements: UMtl has the largest AI research facility in North America, and $100M in spending announced, and ElementAI has raised hundreds of millions so this is no joke.

But the winters are very cold. And salaries lag. And taxes are high. Healthcare is universal and you will get service ... but it's not as good as in the US when you are covered.