Well, I used an M16 in the desert and jungle, and I am going to vote for the AK. Here are my reasons why:
1. It is accurate enough for anything I would need it for. If I am shooting farther than 200 yards, I will have neither an AK or an AR, and if my bolt-gun is not handy, I will be running, hiding or some combination of both. Inside of 200, I can shoot MOBG (minute of bad guy) offhand all day long with either.
2. Reliability. While I never had any serious issues with my issued weapon in the Corps, I would not feel comfortable starting an ambush with an AR or M16 that had not been cleaned in the last month of combat (or 1,000 rounds, whichever comes first). Up at my cabin I had a few friends try to melt my AK by shooting a case of Wolf through it. They failed, the AK never did. While I firmly believe that the AR platform performs just as well as anything with proper and timely cleaning, I prefer a weapon that doesn't require any cleaning to go bang every time I pull the trigger.
3. Cost. I have bought two SAR-1's and dozens of 30-round Bulgarian waffle magazines for less than the cost of one AR and ten 30-round USGI mags. Also, 7.62x39 is cheaper to shoot.
4. Terminal balistics. I saw too many people take multiple hits with the M16 before buying the farm. Bigger is better, just ask you girlfriend or wife.
5. Because the thought of me, Mr Average Joe, clean-cut, law-abiding citizen owning an AK makes the Brady Group and the MMM ladies just about pee themselves.