We used this one: RV Consumer Group - We Rate RVs
. Used their stuff to create my inspection list as well as figuring out what to stay away from and what to look for. Seems most manufacturers have good build days and bad ones, even when they're highly rated overall. Although I wasn't really looking for a Keystone Montana, the unit we found was not only clean and without any blems, it didn't have any structural flaws or problems. After about 20k miles in two and a half years, it's still that way. I've not tried the others, but do highly recommend RV Consumer's Group.
2010 Montana 3665RE, wet bolts, etc.
2006 Ford F350 Diesel Dually, air bags, Softopper, Aeroshild, etc.