I really like the loner characters, most of the time. The ones that aren't very sociable, but still have a deeper insight into any given scenario because they can look at it from an outside perspective. There's often an aura of mystery surrounding them, which makes you want to get to know more about them, but their stand-offish-ness makes it hard for anyone to get close. But that just makes those moments all the more worth it.
First example that comes to mind is good ol' Carmen Sandiego. Mysterious, AND classy! 
Of course, let's not forget the grumpy loner either.
I think another thing that I find endearing about the loner archetype is that they often have the funniest lines. Because they don't speak very often, the writers wait for the perfect opportunity to give them a line to solidify the punchline.
So, yeah. That's my two cents. 
