T2E
On your example Europe to SE Asia. The 777F can haul max. payload (107.5) up to 10.5 hours of flight. You'll therefore find that the 777F is also able to haul 90 tons, and will burn around 105 tons getting it there. Makes the fuel burn per kg. of freigh carried even better than in your example.
Do agree, there's no single answer to what's best. But if you can live without a nose-door, the 777F will - at present - deliver the biggest bang for the buck.