Elijah Wood in The Lord of the Rings: The Two Towers (2002)
FOR: Frodo is an ''everyman'' who voluntarily put the fate of the whole world on his small shoulders, and was probably the only Fellowship member who could carry the One Ring for such a long time, without being corrupted. We also spend the most time with him, during the course of the story.
AGAINST: He failed at the very end, by claiming the One Ring for himself (even though, he sort of managed to indirectly save the day - see Gollum entry for explanation).