I have a FR Wildcat. It is very nice and we really enjoy it. Wildcat is certainly not a higher end RV, but all brand quality is on a sliding scale. Prior to purchasing the Wildcat, I was very interested in the Keystones. When you ask the question about Keystone vs Forest River, that is really not something that can be answered. Both makers have several brands ranging from low price points to high price points. This usually equates to quality level.
I think the materials used play a huge part in the quality, but I think the construction process is very similar for both makers. You just have to choose your price point, and decide what is important to you. If you are looking to spend $22,000, you can get into a much "nicer" used model. I would look around a little more in the used market with that kind of budget.
Good luck with your search.