Seekins ATC...Surefire SOCOM/762/etc...PRI/MSTN QC .308.
All of the above are great options in no particular order. I have used them all and they all work well depending on your budget, expectations, etc. Of those three, I have the least time on the Seekins, but it is quickly gaining favorite-status as I've been using it on a lightweight 16" Armalite AR-10 I built in .308. It does an excellent job of negating muzzle climb and keeping you on target for faster follow-ups and otherwise reducing perceived recoil (not that a .308 gasser really has all that much if properly equipped/configured).