IMO, AR buyers spend far too much time obsessing on bolt carrier groups, grips, muzzle brakes, etc and not enough worrying about basics that help a person shoot well.
I've seen people obsess about BCG's and whether hard chrome or nitriding is better, while keeping some piece of crap GI trigger group that feels like cold chunky peanut butter under one's finger. I see people plaster and festoon all manner of nonsense on four-way front handguard rails (including rail covers to keep their hands from being turned to hamburger), yet they scrimp on a good quality barrel. I've got BCG's that range from GI to the latest gee-whiz nitrided nonsense. They all work. Pull the trigger, they all go "bang," the bolt comes back, the case ejects, the next round gets fed, the bolt goes into battery and we start again.
Get a decent BCG that meets government specs. Oil/lube the stupid thing and be done with it. Put the money you save into a good two-stage trigger or a good quality barrel.