On my first play through in a RPG, I almost invariably always go good. Specifically because evil characters tend to get dicked on XP and loot, and playing it good lets you pick up more of the side quests and what not, so you get to explore the game a bit more.
Every play through after that though, I'm usually an utter bastard.
With KOTOR, I played it good, using mostly self-buffing neutral powers so that my dual wielding jedi sentinal would turn into a giant whirlwind of lightsabery death, however I dabbled in some dark side powers, mostly due to a bit of a min/maxing habit. Plague was just way too damn good to pass up.
-12 to physical stats PLUS they get slowed AND it has a DC of 100? This power makes every boss fight a complete joke.