i've lived in both china [as a child] and canada and visited usa on occasions [but watch cnn so
] and i couldn't claim any place was much better than another.
I prefer liberal and Canada definately offers that nevertheless there are huge problems with it's education [teacher unions = lower quality teaching, no competitiveness, too relaxed etc.] and health care [free=10 year waits for any major surgery].
Despite that, the only reason why i would consider moving to usa in the future would be for money. It's the only reason but its a good reason.
Both countries also have incredibally good traits, however both are FAR FAR FAR from perfect so the best thing to do is to assess your values and then decided on the country. Just never be so naive as to buy into the propaganda that the gov. cranks out about that country.