Honestly, Boromir has always been my favorite character in the books and films alike. My rationale is that he is the most human of all of the characters, which I suppose makes sense when considering the fellowship was Boromir, a Maia, four Hobbits, an Elf, a half-Elf, and a Dwarf.
The idea of the Ring really taking grips on Boromir really fit with me because I believe that any human put into Boromir's position would likely attempt to take the Ring for him or herself...and probably try a lot sooner than Boromir. Boromir was a character of high morals and was resolute, which really expands the power of the Ring as well.
I tell you what...any human who says they would decline a shot at absolute power is a blatant liar. That, to me, makes Boromir the easiest character to identify with and thus the most interesting.
From Boromir's death, I found Eomer to step in as the most interesting character. He had no interactions with the Ring, but he was almost the same character as Boromir and I believe that if he was in the Fellowship instead of Boromir, he would have fallen as well.
Boromir's last act of heroism did indeed vindicate him and also showed the conscious of humanity.
-wtk