Viking Tactics or
Emdom adjustable models are both good. They're two points with one hand adjustment, perfect for shoulder swaps and tightening up to go hands off the gun. I've had a pretty good experience the Viking Tactics, but don't like the metal ALICE pack hardware (tiny spring can break). Try the Emdom. The key to success with slings, IMO, is retention without having something to get caught up in. Three points are for goofy chumps.
I'm not a gun expert by any stretch of the imagination, so I'd suggest waiting until Slims or Walt sticks in their head in and drops a suggestion.