Depends on you definition of "good campground". My definition is if it's not a KOA, then it may not be a good campground. I've camped in dozens of KOAs, and was never in one that wasn't a "good campground".
In the Niagara Falls area, there is
the KOA at 2570 Grand Island Blvd, Grand Island, NY, 800-562-0787
The KOA at 12250 Pletcher Rd. Youngston NY, 800-562-8715
The Good Sam at 2405 Niagara Falls Drive, Niagara Falls NY, 716-731-3434
Canada side requires a current passport and some hassle crossing both ways. And be damn sure you don't have any guns or ammo or dope anywhere in the tow vehicle or RV. And no more than a carton of cigarettes and a jug or two of booze. Last month we crossed into Ontario at Port Huron near Detroit. They asked if I had any guns, and I told them I have several pistols, rifles and shotguns at home but none with me. They still spent a half-hour with two ladies going through my small TT looking for guns or ammo, and maybe for dope? (They didn't find anything.)
But if you want to cross over into Ontario, there is a KOA at
8625 Lundy's Lane, Niagara Falls ON, 800-562-6478