Oh Samuel, how could someone so wise and dedicated to the study of the Word be so misguided? The AK47? Brother I am approaching you man to man as required by scripture when a brother has fallen. Please don't make me call in Daniel. I'm kidding of course, sort of. The AK is perfectly acceptable rifle for 100 yards or less and it will always fire no matter what. Also the ammo is very inexpensive so can be stockpiled.
A quality AR is accurate out to 500 yds, although the lethality of 5.56 is questionable at that range. It will also always fire as long as, it is periodically cleaned, the dust cover is kept closed as much as possible and you use good magazines. I Allied countries it has the advantage of using the dominant cartridge so that you don't have to stockpile much ammo or magazines as they will always be available.
In a perfect world I wouldn't choose the AK or the AR-15 but rather the AR-10 which was the original form of the AR before the Kennedy administration and a drunk Air Force general got a hold of it. The AR-10 fires the powerful .308 and is the perfectly balanced main battle rifle, but alas ammo and more so magazines will always be scarce in a crisis so the AR-15 becomes the overall winner.