From the "current" times, Master Qui-Gon Jinn, the only true 'gray Jedi' of the movie era. I've of the opinion that, had he survived his encounter with Darth Maul, Anakin would not have turned to the dark side. This is a biased opinion though, as I've read (and own) the entire Jedi Apprentice series featuring Obi-wan and Qui-Gon.
Actually, I really look up to him, which is kind of weird considering he's a fictional character... but there it is. His teachings, his faults and his strengths, he's what made the prequel movies worth watching for me.
As for the Old Republic (a few thousand years BBY), I admire... the Jedi Exile and Atton Rand. I played KotOR II under the impression that the Exile had PTSD. (I don't know why or how the idea got into my mind, but there it is.) The Exile did what she had to do simply to survive.
KotOR II in general is a deep, dark story. The protagonists... are all
anti-heroes.
Atton Rand... is one of my heroes. He's a murderer. A drunk. A gambler. A swinger. A sith. Worse than a murderer, an Assassin.
The Assassin. The Best (if not one of the) that worked under darkside!Revan. Yes, it took a woman sacrificing her life for him to see himself for what he was, but he could have stayed where he was--what he was. But he didn't. He stood up and turned away. He ran from the evil that could have consumed him.
Some people call him a coward. I admire his courage for what he did. I admire his ability to fess up to what he did, despite the threat of retribution from the Exile.
I could go on but I'll leave it there. =)