I’ve gone full circle with AR-15 rifles. I originally bought a Colt Hbar standard A2 (fixed regular stock & fixed carry handle). I used that to practice before leaving for Army Basic.
I ended up selling that when $$ got tight and bought a Bushmaster 6.8 “M4” (collapsible stock & flat top receiver with removable carry handle and a fixed front sight) when $$ became available again. The bushmaster functioned fine, but wasn’t all that accurate. It was a completely stock gun and the accuracy improvements I wanted to do (free float handguard & trigger) were only going to get me so far.
I sold that rifle to fund buying a DPMS 308B (fixed regular stock with a flattop receiver and no front sight. Now that rifle was really something. I was able to hit targets at 700 yards as fast as I could pull the trigger with that rifle and it was a lot of fun, but it was heavy and cumbersome not to mention a little more expensive to feed. I put a timney 3# single stage trigger in this gun myself and it was simple to do and made a huge difference. I had to sell that rifle when $$ got tight with the news of a baby.
Since then, I bought a DPMS complete lower (collapsible stock), and then a DPMS complete upper (flat top receiver with no front sight) in 223 as $$ became available. The DPMS upper has a free floated bull barrel and it’s easy to put a scope on it. I haven’t fired many rounds through this rifle yet, (less than 200) so I consider it to be barely broken in. I haven’t done any real accuracy testing yet, but will after deer season. By putting it together myself I was able to setup the rifle exactly how I'd want it and it cost me under $750 with everything being brand new.
Those are the rifles I’ve owned and am familiar with. I don’t really get into lasers & lights on a semi-auto rifle, but that’s just me. The big items I look for are a free floated barrel (R-15 has that) and a flat top receiver (R-15 has that). There are a lot of guys doing their own camo patterns with different spray paints, but if you want the professionally done look I’d go with the R-15. I was thinking that DPMS made the R-15’s especially since the R-10 in 308 is the DPMS design.
In any case I think all the Colt, Bushmaster, and DPMS rifles are great and I wouldn’t hesitate to buy any of the rifles I’ve owned again.