Carol, we took the Cambridge factory tour today. Definitely a quality-built (but pricey) product!
I agree with Carol that the Cambridge is the top of the Keystone line. If you look at
www.keystonerv.com you can see all Keystone brands and judge for yourself.
Second, in my opinion, is the Montana and maybe the Everest at the same overall level. The Everest will have a bit more eye candy, nicer appointments, etc., but the Montana has the better build quality. For example, you will not find an attic vent builtin to the Everest but you do on the Montana. This is not your usual inside vent but a vent to vent out any moisture in the roof area and prevent the resulting damage from dampness. I asked a Keystone rep (we're at the Keystone factory) on Tuesday and was told the same thing I was told a year or so ago. Both the Montana and the Everest have nearly identical overall budgets. How that money is spent is as noted above.
Below this level I'm not sure of which order they would fall.
The above is all just my opinion based on my understanding.