Well not only is the M16 more accurate, our infantry actually uses the M4 now. Look it up online. It's smaller than the M16, but still as accurate at 300 meters. It has a laser sight(well you can technically put any sight on it that is compatible with the picatinny rail system). There are almost infinite attachments for the front handguards as well. It also features a collapsible buttstock.
The only excuse I've heard for the 5.56 we use is for the purpose of maiming enemies, which we can later interrogate. I think that if we weren't in Iraq that wouldn't be as useful, but it just happens to fit the situation.
I'd say the only thing the AK has going for it is the durability and the larger round size.