Southwest Airlines is indeed the literal winner here. However, their points (trip, not mileage based program) do expire and so you have to be pretty active with them to get benefit out of the program. With WN award availability is starting to become an issue on a level similar to other major US airlines, at least if what I am reading on the WN forum is representative. They are also not going to fly everwhere in NA some of us need to go. For some, using them as their domestic airline and using a credit card program like Thank you points to get an occasional free international business class trip might be the way to go.

As already implied in this thread, Delta is leading the way to putting award ticket programs in the toilet (right now I calculate that using Skymiles might be a reasonable option for less than 5% of my trips and that percentage is still declining). With Delta it is not just the surcharges and other added fees of all kinds but all kinds of mileage requirement surcharges on award tickets depending on the routing and the airline combinations.

In summary, there's no really perfect answer to your question; you do get out of a lot of the fees and hassles though if you fly over 75k or 100k miles with your primary airline (i.e., your status is at their highest published tier).