User blog comment:Xornpool/Worst and Best DF User/@comment-3242083-20110825221922

I think it is unfair to count Kalifa or Kaku as "worst" users. At that time they had their ability for like an hour (and still managed to control the fruit somewhat well).

As for the best users, the Admirals obviously take the lead, basically because they are the only ones where we can somewhat confirm their "perfection". Whitebeard has probably trained the Gura Gura no Mi to its limits as well, but thats just an assumption.

As for the worst user, Moriah takes the cake (by far). The Kage Kage no Mi is extremely powerful, yet he fails to take proper advantage of it. Maybe he got the hang of it in the New World.

Then there are characters that could nearly rule the world if they wanted too, but don't because they simply don't have the ambition for it.

Perona's Horo Horo no MI defeats basically everyone with next to no effort, and the few left are so weak that they should be no real threat. Yet she simply isn't the type to do that for real.

Next is Kuma, with the ability to repel everything and sen people across the world, even against their will. Another godlike ability crippled by its user, now after the Pacifista transformation.