Brewster I think had a positive effect on the squad, not necessarily in terms of leadership though. Moore no. Anel was soft, Vini is the only one I would say definitely is a leader. You can tell Peck thrived next to him.
As much as it pains me to say, Jack Robinson was probably the closest thing to a leader last season, he just isn't at the standard required and was also prone to a rush of blood, along with the WWE shenanigans on every corner.
Ben Mee is a clear choice as captain for me. Frequently described as a model pro, who always gives his all and he is very experienced. I really, really hope Wilder doesn't deploy him in the same manner he did Rob Holding (i.e. never), I really feel he is key to turning things round.