The Armalite has been around longer, and can use modified M14 mags for 20 round capacity. The Eagle Arms equivalent is moderately(for the type of rilfe) priced.
The DPMS is a relative newcomer, but has been getting good reviews. It can use the SR25 mags for 20 round capacity, but these are pricey.
Unless you are made of money, don't even bother with the Knights SR25. A great rifle for sure, but at least double the price of the others.
ASA? Absolutely no customer service. If they ever got the version that will accept FAL mags off the ground, that would be tempting.....