For about a year I flew around 30+ flights with SW. I had signed up for their card as did DH and we both got companion passes for each other. It was worth it at the time for us.
The year after we switched to United because SW has a lot of layovers from West to East and United is frequently Nonstop. We could expect at least one if not two plane switches with SW, then we could expect to be in different boarding groups if we didn't set an alarm and check in asap in tandem. It was exhausting.
I have the United credit card which means I get two bags free and through spend alone I'm Star Alliance Gold, which means I also have access to Star Alliance lounges, am boarding group 1, and get to choose my front seats for free.
I mainly fly on points, ie, I don't pay anything more than security fees for my tickets almost 90% of the time. Also if you pay with points and don't check in, you can change your flight around for free, say if you decide to leave earlier or later. Basically flying on points with United is fantastic and I highly recommend it.