I went with V3, myself. It was hard to decide between the two as there is a decent cost saving. Went for the more more expensive in the end because the color version helps distinguish between muscle, tendon and bone. With the 'grey scale' V2 it's not readily as easy to see whether you are referencing bone or muscle.
No regrets since purchasing V3. I've used him for many ZBrush sculpts as 2D anatomy reference always needs a 3D 'physical' cross reference.
