I've got a Bushmaster A2, but don't use it for much of anything. I bought it because it reminds me of the rifle I used when I worked for Uncle Sugar.
So far, it's been dead-nuts reliable. No issues at all. I did take a carbine course and qualified with it, but mainly I use it for teaching grandkids to shoot. The grandkids think that they earn serious cool-points when I let them shoot the AR.
It is a very accurate rifle, much more accurate than I'm able to shoot it. I don't have any optics on it, just the bone-stock sights that came with the rifle. The trigger isn't great, but it's upgraded easily enough.