I think Ouki is the best I've seen so far. (up to ch 230)

Even though he dies in a fight against the Zhou, the way he taught Shin to become a general was awesome. And even though he looks like someone really bad, sometimes we get to see a friendlier part of him.

I really hate Kanki...

those eyeballs..... ;-; but he's kinda awesome too in his own way

And sorry for the grammar in the title, I know it has to be who is....