I've used several Armalite LPKs because of their unique bolt stop.
https://www.armalite.com/SACItem.aspx?Item=EX6575
It is flat and longitudinally serrated all the way down to the lower part, which makes it somewhat easier to manually activate the bolt hold open function without increasing the snaggability of anything. It also eliminates the area where GI-style bolt stops get thin, so it's a little beefier, not that there's an epidemic of bolt stops breaking there.
I'm trying out a Geissele, but haven't made up my mind on which I prefer. My default is to lean toward less stuff hanging off the gun unless there's a really good reason for it.