From CNNSI:
The only thing missing from this picture is the clue the club doesn't have about how to assemble a pitching staff. The park is new without being too gimmicky (save the Power Stacks) and there's plenty to do before and after the game. Cincinnati has always been a great baseball town. Reds fans deserve better than what they're getting on the field.
Amen to that.
Ahead of Great American was Miller Park (Milwaukee), PNC Park (Pittsburgh), Coors Field (Colorado), Angel Stadium (LA Angels), Turner Field (Atlanta), Busch Stadium (St. Louis), and Citizens Bank (Philadelphia).
Of those ballparks I've only ever been to PNC and Busch. PNC is the best park I've ever been to, easily, and Busch was a pretty typical cookie cutter. I'm guessing it's ranked so high largely due to the winning product on the field and the fan base.