Which member of the Fellowship could bear the Ring longest without being corrupted?

[Beren87]

I have always had this notion that Hobbits have a unique ability to resist the Ring longer than the other races. I am not sure whether there is any justification for this in the books

It is justified, and you are correct. Those with a simpler lifestyle are less prone to the influence of the ring. The main example of this is of course Tom Bombadil.

I would say that Sam would be the least influenced of the Fellowship, but the person that would actually make it with the ring to Mt.Doom and still destroy it would be Aragorn. The hearts of men are easily corrupted, that's true, but the heart of a true king is not the heart of a normal man. Aragorn, to me, shows more of his elven blood than he does that of his mortal lineage.