[The Saucepan Man]

An interesting question indeed. But there are really two questions: Who would have been the most likely to seize it off Frodo? ... and ... Who would have been the most likely to succumb as Ringbearer.

As to the first, I think none of them. All of the Fellowship except Boromir accepted the premise that the only way to defeat Sauron was to destroy the Ring and that anyone who sought to use it against him would be corrupted by it.

As to the second, this would only come into play if Frodo was killed or succumbed to the Ring (and became another Gollum). Of course, the next best Ringbearer would be one of the other Hobbits, since Hobbits are the most resistant to its powers (as Bilbo and Frodo proved). Most likely Sam, since he wore (and used) it and was able to return it to Frodo. Then either Merry or Pippin. Then probably Legolas, since Elves are likely to be the next least resistant (although Galadriel recognises that she would become a Dark Queen under its influence), and then Gimli. The least likely Ringbearers would be Aragorn and Gandalf (surely we have to include Gandalf as he was one of the nine and came back as Gandalf the White). Both refused the Ring recognising that its power would corrupt them and, as a rule of thumb, best to keep it away from the most powerful, who would become the most powerful of enemies.