Well, not much competition here.
Ever since I've entered the idol fandom, Takitty has been the leader of MoMusu.
I've heard that Yossie was a good leader, but I've got no benchmark to compare with.
Now if it had been between the current H!P units, would've been more food for thought. I have a definite bias towards the Buono! leader, but I think I'd end up calling it a draw between Captain and Maimi.
Heck, I'd probably call it a draw and call it both of them. They're also another fun, if uncommon, pairing. Heck, they form a manzai - Captain as the tsukkomi and Maimi as the boke. 'Twas fun watching them MCing during one of Mano's lives.