I am a fan of KOA'S, when traveling with the GD. Traveling without the GD, state parks are what we prefer.
KOA'S all tend to have some sort of kid activity, pools, playgrounds etc. Very important to the granddaughter after a long day traveling. And sight seeing
We really like the nationwide reservation system, as we do not plan out where we will be from day to day. So very nice to figure out where we want to be the next day, log on and make a reservation. The night before.
I agree they are not the cheapest, nor are they the best private park in any area. But we have found the further they are from a big city, the closer to a tourist attraction, generally the better they are.
Have run into a couple of snarky staff, but the same could be said for any park, private or not.
So yeah we kind of like them, as a general rule.