Here are mine;
Best overall: VV1, can't beat the classics.
Favorite to play: VV3, I love making a new chief and having them boss everyone around!
Best graphics; VV4, my hour playing it prooved that to me rather quickly. X3
Hardest to play: VV2, mainly because of the algae... I've lost several good tribes to that stuff.
Most improvement: VV4, graphics-wise and gameplay wise.
One I could buy if I could only buy one: VV1, you still can't beat the classics.