"I actually have made a case that the M16 family of rifles is the best American service rifle."
-- Caleb Giddings
I would go further, and say I honestly don't think there is a credible counterargument.
The concept of mass formations of individual long range riflemen, is simply wrong. That's what all bolt action service rifles (like the 1903 Springfield above), and even semi-auto battle rifles like the garand (below) were meant for.
The modern infantry fighting concept, and the doctrine implementing it...
...Small formations composed of well trained, independent but mutually supporting fire teams, with a mix of a few light/medium/general purpose machine guns (possibly some grenade launchers, and light rocket or light mortar support, depending on the environment and situation), a few designated marksman or other longer range capable individual riflemen; and the great majority of troops armed with actual assault rifles, firing an intermediate chambering, light enough to carry a large ammunition load, and with low enough recoil fo fire accurately and controllably in short automatic burst; fighting with shoot and maneuver general tactics...
...has proven to be a generally superior infantry concept and force structure, basically in almost every way and almost every terrain and situation. Period.
The M14 (as pictured in two versions above) is not suitable as the general issue rifle to most troops, under this concept and doctrine.
The M16/M4... is... period.
It may not be the absolute optimal assault rifle system and solution (particularly the 5.56 chambering) for this modern infantry concept and doctrine, but it's the best anyone has actually gone to war with in the last 60 years... And has been the American service rifle for as long as this modern infantry fighting concept and doctrine have been employed by the U.S. (we were in the process of slowly transitioning to it during the Korean war, and even early in the Vietnam war. The terrain, environment, situation, and opposition in Vietnam; essentially forced us to complete that transition, on the spot. We had to rapidly iterate through multiple experiments wifh the force structures, tactics, and equipment, necessary to fight that war; not really coming to what worked... or at least what failed the least... until quite late in the war).
The AK platform is more well suited to the concept and doctrine of mass infantry, in larger elements of relatively poorly trained and inexperienced conscripts, that has generally been employed by Russia, China, and other Russo/soviet influenced armies. But it would absolute NOT be better for the American/Western European modern infantry concept.
I really don't think anyone could credibly argue otherwise.
