That's very tough to answer objectively and subjectively...
Naturally, there are greats... the Enfield MkIII, Garand, M14, M16, AKM... or newer ones of the SCAR type.
Me, I'd put the AKM near the top of the list for the simple fact it been used succesfully around the globe for nearly 70 years and has been the most manufactored small arm in history. However, many will say that doesn't mean much for selecting the BEST ever... The M16, in later models is a hell of a weapon... but IMO it falls a little short of the AKM. Not only the gas system, but the caliber... 5.56x45 isn't what it was supposed to be, it falls shy of expectations past 300m in the M4 platform. Although, within 300m... it works very well against soft targets.
The Garand and M14 have the knock down power needed to reach out to 500+ meters, as well as the power to punch through cover... to an extent. However, magizine capacity is limited by weight and bulk. Ups and downs I suppose, the 7.62x39 is sorta a compromise... it has power to punch through light cover within 200m but it drops off bad past 300m, making accurate hits difficult. Again, I'm biased and prefer the '39 over the 5.56... to each his own.
This is a tough one... I must withdraw my consideration for BEST, I can't choose.
