Get both!
If they're still legal once I have the money, I'll get an American AR to awkwardly share space in the closet beside my AK.
But for the first, I'll throw in my vote for the AK, for a few reasons.
They're simple. If there's a problem, you just need to remember what you did wrong. The parts are big and clunky and not prone to collecting crud in nooks and crannies.
Reliability. See above. The inside has big open spaces, where any schmutz inside can move to instead of jamming it.
The piston system is probably the best in any rifle. As a an engineer in training and at heart, I hate, hate,
hate the idea of just routing exhaust back at the bolt. Get a piston AR design with a few channels to shove crud away, and it would be the perfect gun. If it didn't cost $2500.
Cost. Gun is cheap, parts are cheap, mags are cheap.
That said, a monkey with a zip gun could outshoot the worst AK, but the best AK will outshoot half the AR's out there. The worst AR will outshoot upward of three quarters of the AKs you can get, unless it was constructed by monkeys. If you listen to the fanboys, the best will magically nullify rain, wind, the Earth's rotation and gravity, and be able to liberate a housefly's head from its body of 47028 meters.
To do away with the stereotypes, any quality AR will work as long as you don't pack sand in it and drag it through a swamp.
Any good AK(*cough*Saiga*cough*) will be able to hit a milk jug at 100 yards and beyond.