oh, you'll hit something!It's choosing what you're going to hit that's the tricky part
and inside of 100 yards, either will get the job done just fine- if you like 7.62x39 ballistics, and will use domestic ammo (or reload for accuracy), then an AR will be more accurate- but shooting cheap ammo will make the AR a club much sooner than an AK.. and you'll lose much of the difference in accuracy.. I agree you can generally get a cheap AK or SKS for less than an AR upper-
the con is you've now got another rifle to haul around- the pro is, you've now got another rifle in case something happens to the AR... I lulled the same question over, and came to the conclusion that AKs come in configurations that are just not possible for the AR (folding stocks, pistols without a pipe coming out the back, etc), so try those out to see if they're to your liking...