I've found that speed trumps everything.
I didn't spend nearly as much time digging and shaping the soil as I did moving it from here to there. I used a dozer, large tractor with FEL, and a tractor with earth mover. The earth mover was the fastest, so I kept going back to it. (although it didn't dig so great.
I guess the ultimate would be a large wheel loader and a dump truck. You can move a lot of dirt with those, and very fast.
