Daniel Defense and Bravo Company are top shelf parts. PSA is budget friendly stuff that 'usually works'....
Um... PSA's small parts come from the same suppliers who supply to FN Manufacturing (also in Columbia, SC) who produces M16s and M249s for the US military. The majority of PSA's barrels come directly from FN.
Hard to call those parts anything but "top shelf". They are at least equal to what is used by DD or BCM.