Nowadays, state parks are becoming less of a value. Some states charge nearly as much as a KOA and with no or few amenities. For us, there is no definite preferences. We enjoy both. Most of our trips are in private campgrounds. Normally at the beach. We do have a favorite state park in the mountains about an hour north of us that we like also. We recently tried a national campground on the blue ridge parkway and survived it. We are considering the outer banks next summer for a week and haven't decided on private campground or one of the national ones. Probably private due to the heat and wanting to run the a/c.