I haven't done overmuch research, but I'm relatively confident in this one. Most research came from Wikipedia.
The FAMAS G2 has an incredibly higher fire rate than the standard AK by about 250 Rounds per minute (at full auto).
The FAMAS has a rear aperature sight - something that can help with sustained aiming-down-sights time.
The FAMAS has a much faster bullet speed - meaning faster travel and higher total distance available.
The FAMAS has room for an underbarrel grenade launcher.
that being said, the AK-47 fires a slightly higher caliber round. But all things considered, a shot to the right place doesn't matter on caliber. With the faster fire rate of the FAMAS, there's a greater chance it will hit its target.
The AK 47 was designed mostly to be cheap to create - which it was. It's cheaper to replace than to repair weapons, but does this balance out the inefficiencies of the weapon? Modern militarys should be able to overcome this difficulty with their funding - as the default assault rifle of a soldier makes a sizable difference in a gunfight. I'd rather be on the side that can put out a LOT of bullets faster and with a rear aperature sight than the one with slightly bigger caliber.
But what say you? I bet there are people out there who know much more than me out there who have thoughts on this debate.