I have a Bushmaster XM15e2s (20" standard model A3 Flattop). I bought a Burris Fullfield II for it, but only use it for testing ammo. Then I put the handle back on and use the iron sights. I put a RRA Two-stage match trigger in it. That's it. A pile of Mags.
No Aimpoint, Eotech, Laser, Flashlight, Bipod, Rails, Satellite Receiver, or Television. I admit to eyeing it with the idea of perhaps installing a Percolator before but didn't go through with it.
The RRA 2-Stage trigger is the cat' meow and I'm willing to recommend it. It has the slightest bit of creep in it and is a full 4.5 LBs, but breaks like a glass rod. I like it.