Location Transport

What cities in the United States offer good public transportation?

I'm considering moving from Atlanta to another major U.S. city. Besides northern cities(people seem to irritable to deal with up there), what cities offer good public transportation? Any place in Florida perchance? Or maybe Texas?

Public Comments

1. The best I have experienced are in San Francisco, Denver, and Chicago. LA is terrible, Atlanta terrible. Phoenix horrible and Dallas horrible
2. I have to agree that San Franciso and Chicago have the best public transportation that I've seen.