There are always quality issues, no matter what...
If you were gonna score by brand, Thor, forest river, and coachman would be at the bottom/
Winnie, Itasca and Fleetwood next.
Newmar, Monaco, etc above them.
These days, a LOT of low cost DP's are running the new light freightliner chassis and ISB 6.7 pickup truck engines. I've no experience myself with these, they are light years ahead of the 5.9's... still, my entry level Monaco is an ISC... they claim more horsepower, but cannot come close to my 1050 ft-lbs of torque...