- ]Khem Val - He offers to eat your enemies. How could I not finish his story? Granted, I got bored with my SI at 45, so I haven't technically finished Khem's story, even though he is at max affection.
- Ashara - The part where you start corrupting her on Taris was the only remotely Palpatine-like moment in the story, aside from the Nar Shadda arc. Plus, she's the only romanceable option for male SI's.
I didn't use Talos Drellik very much, but he was a cool character as far as I got with him.
- Vette - I like the way her voice-actor sounds, and her dialogue is usually witty enough to enjoy. Her story is pretty interesting, too. She's a very useful character for tank specced Juggernauts, too.
- Quinn - I loathe Quinn. He comes off as a prissy ponce with a stupid mole on his cheek. I sometimes use Quinn for the heals, but I usually send him off on missions.
- Pierce - I really like the character's story, but I have absolutely no need for a tank companion.
- Jaesa - Lightside Jaesa is pretty meh. "Can I speak as a Jedi?" "No. No, you may not." "Well, anyway... when we turn all the sith into the Jeedais..." "How the hell are you still a Lighty anyway? I killed your first master, and your parents, and then I turned Nomen Karr into a raving Dark Side loving lunatic. Further, how the hell do you still think I am an agent of the light? I killed your parents for sport.
I just started a Smuggler, so the only companion I have there is Corso, who seems pretty cool. Sort of like a space redneck or something.
The SW has the most memorable companions, so far. The SI's companions are all kind of meh.