This one seems like a pretty good value, assuming a quality build of course...
http://www.ruger.com/products/ar556M...eets/8514.html
18" Rifle Length 1:8" Nitride 5R Barrel
Magpul MOE Furniture
MLOK 15" Free Float Rail
Two Stage 4.5 lb Trigger
I could see myself picking one of these up if the street price goes sub $500... preorder here is not much more than that right now....
https://www.sportsmansoutdoorsuperst....cfm/ID/199005