I doubt any of the above will come close to the accuracy of a Les Baer AR 308 sniper rifle.
As a related possible topic
Trying to get a really accurate 308 AR rifle that can be considered a carry gun defies reality.
The best 308 carbine, IMO, would be a PWS MK214 or 216 (14.5 or 16" barrel) with it's simple piston it is reliable and small enough for carry
The Knight SR25 or LBC 308 sniper would be the better long range shooter but by the time you put a big optic and Bi-pod it will be 15-18 pounds
The right tool for the right job and in this case trying to combine them borders on pointless
Wulfmann 