While I like both platforms, I'm an AR-15 guy if I had to choose. There's nothing wrong with AKs, I love them too. I just find the ergos of the AR-15/M16 platform all around better. I don't have any problems with 5.56/.223 caliber, especially since I'm not limited to FMJ ammo myself. I much prefer a lighter, flatter shooting round.
I think the main difference I see between the two, is an m16 is better if you are equipping a person, the AK is better if you are equipping an army.
As for long distance shooting with AK's, I know they can be done. I've seen it done. I've seen my buddy hit the 440 yard gong with his wasr-10. The trick is knowing the range and your holdovers. Them problem is, with a standard 50/100 yard zero, after about 200 yards, you start measuring the drop in feet instead of inches.