Aside from all the modern stuff, I reckon the "Rifle, .303 No.1 MkIII SMLE" has got em beat! It has the range, accuracy, punch, high rate of fire and great mag capacity, robustness and reliability.
It can launch grenades, and a bayonet can be attached. The sights are easily adjusted, and it can be fed from chargers, and there is ammo from drill, blank, ball, tracer, AP, API to name a few.
It has sling swivels, a stacking swivel, well placed safety, a butt trap (with oil bottle and pull-thru), and from an armourer's point, easy to work on, and no plastic!
In the hands of a trained Rifleman, the results were impressive. From Bullecourt in WW1, to Kakoda in WW2 to Kapyong in Korea, and even today here in Australia, the Lithgow SMLE is still in the system, has a NSN, but is obsolete.
Plus the Lee-Enfield is still around (in service in Africa and India and other places) owned by thousands of private citizens worldwide, and has already started it's third century.
The rifle is truly in a class of its own!
Cheers,
Wes