Well, Sam is the heart of the story, so I'd be inclined to say him. Without Sam, there is no way in hell Frodo would have made it to Mordor; from that perspective, he was by far the most important member of the Fellowship. He's loyal to Frodo to the end, and without him the Quest would undoubtedly have failed.
Then again, I did really like Aragorn as a character, mainly because I cam sympathise a lot with him. He's enigmatic and reclusive, and largely prefers his own company to being with others. The fact that he's really good in a fight and is wise on roughly the same level as the Elves helps a lot as well. It's interesting to watch him develop as the book goes on, moving from being a Ranger to being heir to the throne of Gondor. It's a bit like an RPG really, considering how much he grows in power over the course of the book. He's not at the heart of the story like Sam is, but he's still a very good character.
esperandote said:
Tom Bombadil because he could haved hold back all Mordor if he wanted
Debatable. Both Sauron and Bombadil were Maiar, so the fight would probably have been quite an even one. If Sauron had recovered the Ring, I seriously doubt Bombadil would be able to hold him and the Nazgul back in a pitched battle; Gandalf was just about able to drive off the Nine, and he was almost certainly more powerful than Bombadil. I think if it had come to war between Mordor and the Old Forest, Sauron would have won.
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