[ProjectArcturis]

I would rank SW roughly in the middle:

Alaska Hawaiian [Delta American United Southwest] (rough tie here) Frontier Spirit

It depends on what you value. If you always fly first class, of course SW is worse. SW does offer a lot of direct flights that no other airlines offer. For me saving several hours in not changing planes is worth a slightly worse flight experience.

Also SW doesn't gouge you when cancelling or changing flights, unlike all the others.