Completely agree with this..
I know youre looking at off the rack AR's.. but if youre talking SHTF scenarios.. this may sound crazy.. but I'd recommend building yourself...
Its not hard to do at all (it does not take a pro.. and only takes a couple of tools.. I could teach a chimp to build an AR in an hour)..
And in a TEOTWAWKI scenario, youre going to want (need) to know how to repair your SHTF rifle.. Understanding not only how simple the gun is, but also what does what, how to repair and/or replace it, I would think would be a critical skill..
Spring kits and other basic replacement parts are super inexpensive.. If youre talking about the potential of owning multiple AR's, I'd have a handful of parts/springs that commonly get replaced (trigger springs, hammer capture springs, extractors, bolts, buffers, etc) after an AR sees a lot of hard use (thousands of rounds).. youre talking a hundred to two hundred bucks tops to have a good supply of replacement parts and springs..
But replacement parts and springs do you no good if you dont know what to do with them..
My basic home defense AR is a pretty basic build.. its a 16" carbine with an aimpoint red dot on top, a set of back up irons, and a high output white light.. and thats about it.. I dont get the guys that strap every object known to man to their AR and create a 15lb "fighting" rifle.. If I were running NOD's I might consider an IR source.. but Im not.. so, I dont..