In my opinion, the M14 is vastly superior to the M16.
1.) The M14 chambers 7.62 x 51 mm NATO, a full-powered rifle round. The M16 chambers 5.56 x 45 mm NATO, a smaller, lighter imtermediate round. Therefore, the M14 has much greater range and power.
2.) The M14 has an extremely reliable mechanism, a feature not shared with the M16. Therefore, the M14 is more reliable than the M16.
3.) The M14 has a longer barrel than the M16. Therefore, the M14 is more accurate and has greater range than the M16.
4.) Both the M14 and M16 are selective fire with full automatic capability.
Rebuttals for common pro-M16 arguments:
1.) "You can carry twice the amount of ammunition with an M16."
Maybe so, but you're going to need three times the amount of ammunition to kill someone.
2.) "If the M16 is inferior to the M14, then why did the US Military adopt it?"
The decision was political. ArmaLite and the military tested the weapon in near-labratory sterile conditions. ArmaLite had lobbyists all over the place, and we were under political pressure from the rest of NATO to adopt to the 5.56 x 45 round.
3.) "5.56 x 45 has enough power to get the job done."
Not true. Soldiers have reported enemy combatants continuing to fight after being shot more than once by M16s. No one gets up after getting hit by an M14.
4.) "The M16 is reliable enough for frontline duty, if regular cleaning takes place."
Every gun is reliable enough for frontline duty if regular cleaning takes place. But the truth is, regular cleaning is not going to take place on a battlefield. Our soldiers need a weapon that can be shot and shot and shot without needing to be cleaned.
5.) "The M14 is semi-automatic, and the M16 is fully automatic."
Not true. Both weapons are selective-fire fully-automatic capable.