Wow, camp on Onan day!
Ours is quiet. I think installation has a lot to do with noise along with tuning as a previous poster mentioned. The microwave is louder when running inside the trailer than the generator. Our Onan was there for us when I remodeled the house kitchen and during power failures. Guess I'm lazy as toting portables around is not our cup of tea, along with refilling gas and gas cans. The Onan has its quirks, but we have adjusted for them. It probably could be better, but we are happy the way it is.
My big noise complaint is the damn blower for the heater. That thing is loud!