The OEM Manufacturers carry their own brand amd I also purchase from OpticsPlanet, Brownells, etc....I use a vertcal grip from MK Machining on my RAW Chassis.
Most ANY...shop that sells firearms equipment...sells AR15 grips !! Google is your friend.
It makes NO...difference what we (in forum land), like, all that matters is what YOU like... ! Since YOU are the one doing the handling...right ? Many like the original laid back angle. I do not, I like a more straight up and down angle. Much like the Colt Government .45 . Or even a "0" degree angle, that is straight up and down. This sorta says, that yes, you may have to buy a couple of different grips to see exactly what...YOU like. Life in the big city !
I have a B5 Systems Type 22 on my Dreamtac that I like. It's a bit more vertical but I find it to be a pretty good fit for me. Good grippy surface, too. They run about $20.