Good call on the Aero lower, I have the Aero Precision AC15M rifle. If you're shooting less than 300m stick with a 16", you won't need the extra length. 4150 QPQ treated mid length gas barrel, smooth recoil, and ya' really only need chrome lined if you're going full auto or run corrosive ammo in the jungle. Check out the Ruger AR556 trigger, you can find them for less than $100, bleep nice trigger. You won't find a better muzzle device for barrel control than the Epsilon VG6 or the Strike Industries J comp V2 but they can't beat the standard bird cage for flash suppression.
My 2 cents