We have stayed in several from just OK to very nice plus many of the state campsites. This is the usual site I start with before looking at RV Park Reviews: Campground Owners of New York - Go Camping New York!
We stayed here, KOA Association Island, a couple years ago and could watch ships on the river heading to or from the Great Lakes 1000 Islands / Association Island KOA | Camping in New York | KOA Campgrounds
. Unfortunately 'on-season' it has gotten pretty expensive for some though we stayed late in the season and it was right on the acceptable price for us. Here's a photo or two of what you can expect:
.....and from the back of our campsite:
If you are near Tupper Lake, State CG's such as Fish Creek Pond and Rollins Pond are great, very busy with a couple hundred sites each but have some length restrictions plus are dry camping only with a dump station.
We are enjoying a semi-seasonal at a small CG at Westport, NY along Lake Champlain as a jump off point for trips elsewhere. There are no length restrictions there (Barber Homestead CG).
Many inside the Adirondack Park borders CG's have been hurt by the Adirondack Park Agency regulations that have made it very difficult to upgrade and expand so are not all in the best of condition which in turn limits their income and ability to provide as good services as you would like to see ....... and I'll leave it at that.