For me, most important would probably have to be location. I don't think I've ever said to myself that I'd like to visit East Micropolis because that's where XYZ RV park is, but I have frequently stayed at XYZ RV park because it's convenient to East Micropolis and I wanted to go to East Micropolis. Related to that, if decent public transit in East Micropolis exists and can be accessed not far from XYZ RV park, that is a very definite advantage to me.
Second would probably be price, at least within reason. If the price is high, I'd sure expect there to be some compensating advantages that justify the price: extra nice sites, etc.
I like some space and privacy, and vegetation/trees between sites. I don't particularly need lots of ammenitites or even full hookups; electricity at the site is nice, and a dump station/potable water fill is likewise very much appreciated. An RV wash station is nice sometimes, doubly so if it doesn't require dumping a lot of quarters in a box on the wall. On longer trips, laundromat facilities are a plus. Pull through vs. back-in makes little if any difference to me.
Although I don't have or generally travel with kids, I do like having them generally around and seeing them have a great time. (That's not to say I'd appreciate them climbing on my RV, of course!)
