Our camping club has an upcoming event at Cove Lake CG in September. It's a TN State Park.
Friends of ours use Big Ridge because it's close to home, but they don't really recommend it, said the sites just weren't up to par with Cove Lake.
I can't recommend either of them since I have never been, but I do know that Norris Lake is beautiful. There are several other TVA lakes within 100 miles of Norris. (Cherokee, Boone, South Holston, Watauga)