With SWA, you know what you're going to get. They are consistent, the employees (generally) seem happier and more pleasant than the perpetually p!ssed off AA/UA/DAL crowd, and best of all (as has been noted previously) there is flexibility with changing/exchanging tickets. No $150 "change fee" (seriously? a few keyboard strokes costs that much?), no cancellation fee, no nickel and dime BS. And the frequent flyer program is just as flexible - have traveled for free a lot. Great website and app, hardly ever have to talk to a human.
I'm a fan, and steer clear of the legacies as much as possible.