Rock River Arms has been on Commerical Row at Camp Perry, if you are going. You can handle and play with their total product line. And the prices are great.
Because the prices are great, I purchased a NM Rock River AR. The rifle meets all my expectations, accurate, reliable, tight, etc. I like the design of their trigger and I have had Rock River NM triggers installed on three AR's. White Oak Precision sent me tuned RR triggers for less than the purchase price of a new trigger. Can't beat that.
One year, a young civilian shooter won the President's (I think could have been the NTI) with a stock box RR. Incidentally, a stock box Armalite was used by the high service shooter (a USMC Reserve guy) one year. I am certain a Bushmaster has done well, I just have not heard of it. Any of these manufacturers make NM rifles that will win the National matches straight out of the box.
But back to Rock River. Excellent AR's.
DSA, I would buy one of their FN's in a heart beat if I had the spare cash. As to one of their AR's, never seen one. They are a good company, so it probably is a quality product.