VoxelSniper returns the best results in my opinion. It has features such as overlaying at a specific depth which can speed up the process significantly.

I do it by hand, mainly because I don't know of any other way.

I do. Have been doing it for 3 years on the same map to create this large island. It will never really be done.

uhhhh... use World Painter to edit pre-made maps, use World Machine to create whole new terrains - realistic style

When you use VoxelSniper for terraforming, haha.

I do terra by hand only using w/e for filling in stuff that I'd rather not be bothered with.

I used to, and I know someone running his own gig who does, but it's extremely inefficient and in retrospect hand-built isn't really better, though I only use worldedit for some pasting, some mass formation constructions and terraforming (the rest is by hand). What you need isn't a handbuilder, it's a person who uses worldedit correctly.

Nop, only the finishing touches, I do everything with world edit, and then add the finishing touches by hand.

i still terraform by hand, because i can't be bothered to learn mcedit. and i only use worldedit to do mass replacements, for example replace stone with grass, or smooth the terrain more than i can

The reason people don't terraform by hand any more is because using worldedit is much more convenient. The thing people often forget though is to edit the worldedited terrain by hand. That's why terrain people make using worldedit often looks less then when it has been build by hand. Also, if the terrain you want to terraform is to big, people often don't have the time to do everything by hand.

I personally just use worldedit to do basic shapes and after that I just place and punch out blocks by hand.