A couple of libreal, progressive, urban cities doesn't change the fact that the majority of America is ignorant and racist.
Go outside of London, Birmingham, Manchester, Liverpool as a minority in England, and you're digging your own grave. I've lived outside of a major city for 5 years (not by choice) and it was hell. Neo-Nazi's and National Front all over the place. Getting called both "Paki" and "N!gger" in the street because they couldn't figure out what I was. One of my cousins went to a sleepy coastal town up north less than an hour away from where he lives, went to a fish&chip shop and was told "We don't serve your kind in here"... and this was just 2 years ago.
So, overall I'd much rather live in the US because there are LOADS of forward-thinking, progressive cities that I'd be perfectly comfortable in. I've spent a great deal of time in LA, San Francisco, Las Vegas, Eugene, Portland, and short periods of time in San Diego, Seattle, Tacoma, New York, Atlanta and I'd live in any of those places. I have friends in Minneapolis, Miami, Philly, and South Carolina and I know I'd be comfortable in any of those places too.
I'd totally live in Canada though too. Vancouver is one of my favorite cities, I would live there. I love Toronto too but I couldn't live there cos of the weather in the winter, lol.