Pain's path abilities, but only if I had the option of using it through my one body like Healthy Nagato. Otherwise, Tobi's warping. Ssj1 Goku's powers from the Frieza saga, or 100% Final Frieza's powers? I know just looking at it seems logical but consider it.
Probably Darkness. I don't know it very well and I'm under the impression that he's weaker than Piccolo, but his power scope is far more practical and useful in daily life and what not.
Let's see. Would you rather have the powers of Wolverine or Colossus?