To me, it is obvious that the best belt fed machine gun of all time is the M2 Browning. Lots of other machine guns have come and gone, but the M2 just keeps proving itself in conflict after conflict.
You know the rest. In the books you have read
How the British Regulars fired and fled,
How the farmers gave them ball for ball,
From behind each fence and farmyard wall,
Chasing the redcoats down the lane,
Then crossing the fields to emerge again
Under the trees at the turn of the road,
And only pausing to fire and load.