That leaves Philadelphia, and Chicago as livable places for me, maybe Baltimore and St.Paul-Minneapolis but that's about it

Seattle? Or too expensive?

Too expensive ):

Hear me out - Mexico City. Excellent transit network, affordable, delicious food and very walkable.

Do I want to have to learn another language just to live in a new place, that is an important question

So that rules out Quebec.

I'm not ruling out Quebec or Mexico, just genuinely I am not sure whether or not I could even learn Spanish/French well enough to be confident and conversational

Actually moving there and having the need to use the language just to get around is generally the best way to actually make yourself learn.