My vote goes to the DC-3....
It carried food, fuel, paratroopers, jeeps, medical supplies, booze, women, generals, admirals, ammunition, spare parts, and even a few L-4 grasshoppers!!
Of course I'm not serious...
Most diverse is the Ju-88. Although not best suited to all the tasks fitted, she did manage to do all of them...
Night Fighter, medium bomber, ground attack, dive bomber, heavy fighter, recon, long range maritime patrol, torpedo bomber, and guided bomb (Mistel component).
Jeff Herne