I have tried almost every grip for the AR variant known to man. I like the Tangodown Battlegrip and have used it for a long time, but my hands are just too big and I cannot get proper finger placement all of the time. The answer to this was the Sierra Precision SPR grip. That was my front runner for a long time, and still is on my work gun. The SPR grip has a built up shelf for the thumb and is very thick on the right, which keeps you from getting too much finger on the trigger. Wrong-handed shooters are SOL, as the SPR grip is built ergonomically for the right hand.
Recently, I picked up a Stark Equipment SE-1 grip from Shooter's outside of Bragg. I like the fact that it keeps the trigger finger from riding too high on the trigger and contacting the receiver. The Stark grip keeps your finger where it needs to be, on the trigger and only the trigger. The Stark grip looks kind of odd, but is remarkably comfortable and extremely efficient at promoting proper grip and finger placement on the trigger. Coupled with a Geissele SSA it's like shooting a different gun.
The Stark Grip is available in FDE, Black, OD, and Desert Digi (similar to desert MARPAT and AOR1). A "fancy sauce" version, the SE-2, has a built-in QD flush cup on the rear for sling mounting. I like this option as it keeps the sling from interfering with your cheek weld as some receiver end plates can do.
Check them out at www.starkequipment.com, and buy them from Bravo Co. USA or Brownells.
Pics to follow shortly.