Ultimak gas tube rail and Aimpoint H1 or T1 with a LaRue mount. Expensive, but quality. A standard model Aimpoint (M2, C3, M3, etc) can also be used, in a LaRue mount also.
The dust cover mounts are generally useless. There is one company- Texas Weapons Systems that makes a worthwhile rail.
The side rails seem to work OK, but place the optic pretty high over the bore, creating cheek weld issues. They are generally the most cost effective, however.
It comes down to how much you are willing to spend and what you are willing to settle for. For plinking, it doesn't really matter what you buy, but you said best. You definitley, however, don't want to go too cheap/gimicky, simply to save yourself frustration.