Best for what ?

Blender and trueSpace offer a plethora of functions (e.g. check out the fluid simulation and sculpting in Blender).

Milkshape3d has a whole slew of formats it supports ...

Download the free ones and try them. See which interface best suits your way of working and then decide.

Cheers,
Andreas

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GameCore / Unity / UDK
Lightwave 9.6 / Blender / Fragmotion / ZBrush 3.5
TextureMaker / PSP-X