Raed
Dr. Raed St. Claire
Yeah hell no on Pique. He's a joker and has a hard enough time keeping himself in order let alone a whole team.
Messi. No. Not for his abilities, desire to win... but for his inability to motivate others. He knows how to motivate himself but I don't think he is vocal enough to motivate others around him when times are tough like Puyol or Valdes could.
Busquets? I think his own personality does him in on this one. It's tragic because he does display leadership qualities and calm but he is so naturally withdrawn and quiet that he would disappear in desperate times and that wouldn't be good.
Iniesta? See Busquets
Masch would be the better choice for me. He's the kind of ride or die tough as nails type that would suit Barcelona for captaincy. He seems to rally people behind him quite well too with his heroism and he is vocal and not afraid to shy away from challengers. If he continues the way he is, he'd be my choice after Puyol, Xavi, Valdes retire.
Mascherano failed to captain Argentina and was so bad at it.