BINGO!

In a huge number of markets, the only nonstop option is SWA due to not utilizing the traditional legacy hub and spoke network.

So in answer to your question "What is it about SWA that people rave about?" often it is nonstop service to a destination where none other exsists. In addition to a lot of other things people have already mentioned. Your still handing them money because they offer a service you desire.