We have flown both. I find them pretty comparble planes are clean & comfortable, service friendly. Only downer for me on AirTran is paying for and selecting seats at purchase (we've never been lucky enough to find even 2 groups of 2 seats together) so we prefer SW open seating. AirTran also charges for baggage. We haven't had a bad experience with AirTran and would fly them again in the future.