I grew up outside of Dallas and live where I always have to have a layover in Atlanta now, and I would have to say Atlanta. It's easier to navigate, especially if you have to go far away to get your connecting flight. At Dallas you have to go outside to catch the tram that goes around the airport, but it's inside in Atlanta. The shopping is better in Atlanta too, or at least it's better than it was at DFW about 5 years ago.