I've got to go with Kor, but only the Kor in Errand of Mercy. I didn't particularly like the re-imaged Kor in DS9. They tried to re-work him as a "new" Klingon, and I didn't think it worked very well. He just wasn't the same.
Don't let my negative vibes about the re-imaging throw you, though. I come here to praise Kor, not to bury him. In TOS at least, Kor *defined* Klingon.
-S'Cipio