We have only ever joined PA and Good Sam. We travel a lot and frequently move so usually recovered our investment in PA within a couple of weeks. We wouldn't travel without it.
However, we don't travel in the summer or high season so aren't hitting the RV parks when they are full anyway. All those restrictions? If you can cut your RV parking cost in half even for a couple of nights, that's usually paid for your membership right there. Good Sam is less useful. Not sure we'd renew next year. A 10% discount (GS) isn't nearly as interesting as the PA 50% discount, to me.