Who would be most powerful with the one ring?

[lord of dor-lomin]

Not sure what order they'd be in, but I'd definitely go with Gandalf, Saruman, or the balrog.

I just don't think that non-angelic beings would be powerful enough to fully harness the power. In the books some of the characters thought they could, such as Galadriel, but that was merely her opinion. I think I saw someone recently post on another thread that Tolkien didn't believe that an elf or man could control the ring and use its full power.