You want the droid. He's a sadistic little killing machine with a couple of blasters, and his dialog is some of the funniest in the game. He's fun if your light-side, and an absolute blast if you're going evil.
Better yet, if you have decent computer use on your main character, you can get a chance to 'repair' him, and make him very powerful. Besides, as you'll find out later,
he actually is an assassian bot that used to be owned by your character.