Favorite episode: Shindig.

Specifically for the line:

Mal: Mercy is the mark of a great man. [stabs Atherton] Guess I'm just a good man. [stabs Atherton again] Well, I'm all right.

I've even wrote a Filk song (to the tune of Godsmack's Serenity...) although I have to say "Reavers Malcolm Reavers" is probably my favorite FF/Serenity filk song. (That was is also because of something which happened at DragonCon...)