All jokes aside, the AK-47/AKM is arguably "the best battle implement ever devised" (More so than the Garand) due to it's excellence in all things required of an effective infantry carbine. Simple manual of arms, reliability, durability, service live, ease of maintenance, ease of manufacturing, all-around intermediate caliber, etc.... as well as filling the role of a SMG, replacing the PPSH.
People like to knock the typical 3-6 MOA that comes with the caliber, barrel harmonics, sighting system, etc, but remember the philosophy of use... it's a long service life, highly reliable bullet hose to be used by conscipts from Soviet republics.. not a precision rifle.