New York City
Hard call for me between New York City and San Diego even though they are so different.
For me, it's San Francisco, by far.
Places like New York and Seattle are great to visit, but SF is the only big city I would want to live in.
In fairness, I have never been to Chicago or Boston, but I'm sure they both suck.
I loved living in Boston, it reminded me of an east coast SF. I'd call it a close race for 2nd between Boston, Chicago and Seattle. One not on the list is Miami, I was only there briefly but I dug the vibe.
How'd Houston and LA get on the list? I guess just size those places are dogs.
San Fran is pretty cool, but it seriously needs about 15 degrees of global warming. I love L.A. and San Diego weather because of the daily cycle. You start out with the sea breeze/marine layer then it tails off into a perfect day.
Spent a decent time in Brooklyn, and working in Manhattan. One of the best cities in the world.