Cost, Functionality, Practicality, Performance, Reliability are probably the most important five. The AR is more easily changed to a new caliber, two pins, five hundred dollars, you can shoot 9mm through it.

Is its demand based on a real market, or is it a niche or price point driving the demand. The mini has a niche in the farmer/ rancher crowd, and the only has $400 to spend crowd. The AR, at $800 to $1200 + for a gun built with mil-spec parts, is in the price range of the M1A, and .308 is just as cheap.

Ruggedness. The AR/M16 has a couple of fatal flaws, that my experience with them has shown me. The aluminum threads in the rear of the receiver where the buttstock screws in are extremely thin, making the weapon extremely fragile, it doesn't even take a good buttstroke to render your weapon useless. The second is double feeds. If your mag ever bobbles and feeds two rounds, there is enough room between the bolt carrier and the top of the receiver for the base of the round to fit. Since the charging handle is not part of the bolt, it will not push the bolt forward or backwards. It can be cleared, but it takes time, something you don't have when somebody's shooting back. Any GI that spent a lot of time on the range has seen that one several times.