Villains. I love them to pieces and always have, so my characters that that blur or stomp on moral lines get interesting. I don't always get to exercise this, but other players in my group get floored by antagonists that I develop.
My good characters are okay, but they don't measure up. I just like how rulebreaking and malicious characters can change things in interesting ways.
Never done NE or CE from the player side of the table, but I would be interested in trying should a good opportunity come up in a party with no good cleric or paladin.