Im really torn on Obi/Anakin. Darth Vader is my all time favorite villain hands down, and watching Anakins fall to the Dark Side makes me tear up every time. But Obi'Wan is the truest character in all of Star Wars. He has the best moral compass of any character in the films. Unfortunately the acting in the third movie for Obi was bloody awful, but this is counter-balanced by Phantom Menace Anakin.
Han Solo would have made this list, but he's already my child hood hero and thus in a category all to himself.
The story of Boromir is, in my opinion, one of the most emotionally moving in all of fantasy (also Sean Bean is a fantastic actor).
Bilbo is simply the greatest character ever concieved, imho.