I love the agent companions. There is not a one I would wish off my ship. They're interesting to me, even Temple, who annoys the hell out of me with her rigid pro-Imperial stance. I will say that it is kind of like running a floating insane asylum, though - no one on my agent's crew is quite right, including her.
The bounty hunter crew is all pretty good at being who they are. Even Skadge, for whom I have a deep and burning hatred is good at being a nasty, predatory, psychopath. I find Mako annoying, but not as much as Temple or Vette.
The Smuggler companions are all kind of boring to me.
The SI companions are also kind of meh, except for Khem and the sweet little archaeologist, both of whom I adore.
Quinn is fun to play with, like a mouse to my SW's cat, and I find Vette extremely annoying. They are really the only SW companions I have interacted with personally, at least. I like Pierce, but my SW doesn't have him yet, so I can't really give an informed opinion.