Personally, I wouldn't want an overpowered skill. To me, such a skill would be as useless as an underpowered skill. It would be like a cheat code that's taking up a skill slot, which could have been better used by a balanced skill.
One of the things I want to see in an RPG is as little useless skills as possible. Of course I don't mind if a skill becomes obsolete once you've leveled up enough, just don't make it useless from the beginning.
All skills of the same level should be equally useful, just in different ways. I enjoy exploring the skill trees and trying out all kinds of "builds", and anything that takes away from that is not something I would want. The point is, if you need an overpowered skill, the game has failed (or you're exceedingly bad at playing it, but there should be proper cheats for that).
