I believe that AF is the only one of the three that uses all plywood vs. OSB. They are also build their own chassis and have it independently certified. They also have shocks on their wheels. Not sure if the others do. One other manufacturer you might have a look at is Outdoor RV which is also built in Oregon minutes from AF and shares the same cassis and other features like 100% plywood. This is the brand we are looking at (and Arctic Fox). They have a few shorter models that we like.
After looking at threads here and elsewhere showing Keystone products and their customer service I would scratch that one right off my list.
If weight and cost aren't barriers for you, AF is probably the best built of the three.