Generally speaking I've come to the opinion that you can't really go wrong when for most people they might as well have bought an AR-shaped bar of soap for the amount of use it'll get.
The problem today is weeding through all the bullshit. this coating, that "enhanced", this other "mk2"... what a pain. So much analysis paralysis potential out there.
20 years ago once you got your head out of your ass you just needed to go buy a 6920, 6520, or 6933 and you could be done. Throw on a "rail" from Daniel Defense (they had one model) or Larue (them too) and an Aimpoint in a Larue mount and you're ahead of the curve.
ETA:
Oh, and get off my lawn!