I’m probably gonna get fragged for this, but I’m _very_ happy with the multi-cal Liberty Mystic X kit (suppressor + 4 mounts) I picked up for $555 at gunzonedeals last year. (It’s up to $605 now, but I’ve noticed they sometimes float down $30-$40 over time.) Stainless 11-baffle core, titanium tube, great warranty.
Excellent full-length 9mm can on PCC’s & pistols. Had to get the booster for pistols, obviously. Useful on carbine-length AR’s, but a dedicated, decent length can will be better. (As people have pointed out, 5.56 AR’s are always gonna be loud; bolts can be pretty quiet.) Does a lot of things really quite well. Pretty easily maintained if you don’t just let it go on really dirty calibers (lookin’ at you, .22LR!). I’m itching to try it out on my new 8.5” 300BO upper with 220gr subs & 150gr supers.
OP is welcome to PM me if he’d like to hear my case for it.