The only kind of companion I want is one that's a competent thief, or rouge. I hate when I'm trying to sneak through an area with a companion and I get spotted because the idiot decided to go Leroy into a group of enemies. That said I think I'm gonna do the same thing I did in Morrowind, Oblivion, and FO3, and that's run solo, I hate companions. And yes, even when Behemoth hunting in FO3 I refused to have a companion help me, I can take a den of enemies out more efficiently by myself than with help.
On the other hand, if it allows for some sort of co-op, I will definitely be helping/being helped by some of my friends. A two player co-op thing (second player would need to get slightly nerfed stats otherwise it would become unfair though) would be insanely fun to do IMO.