I've got a couple AR's, one piston (Adams Arms) and a DI (DPMS). Both have been flawless but I have to admit that I always really hated cleaning the DPMS mostly because of the poor finish on the bolt carrier group.
A few months ago I swapped out the BCG with a Nickel Boron BCG. Never really timed my cleaning time but I'd bet that this cut it at least in half.
I think AA also uses Nickel Boron but since it doesn't get nearly as dirty it's never been a problem anyway.
This sure was a big improvement to the DPMS however.

Try a black Nitride sometime. Easy wipedown and no surface coating to peel/flake.

I've got a nickel boron BCG and it's the hardest one to clean, I'll not buy another one.

the rest are black nitride and are much easier to clean.

I just shot 800+ rounds completely dry with a FZ bolt over 2 weeks. No failures at all.

Cleaned up easy enough.  It did in fact seem to run cleaner dry. Surprised me.