Do not cheap out on a BCG. If in doubt, don't buy it. Unless you KNOW precisely what you want, and why, and are confident in your decision (since you are posting to ask, this does not seem to apply to you) get something that is Carpenter 158, HPT, MPI, shot peened, from a reputable manufacturer/retailer. This is a known-good standard. The $100 or less AIM BCGs specs are usually scary.
I would get a 'mil spec' (plain, no extra money on NiBoron or anything) Spikes Tactical or a BCM. I wouldn't pay over the $169 BCM charges, as the absolute maximum, for any AR BCG. There are plenty of other good/very good choices but these two (Spikes/BCM) are very good, priced right, and almost always available.