Elbaph Main Villain

I still don't understand who will become the main villain of the Elbaph arc, will it be Gunko since she was one of the first holy knight to come to elbaph or maybe sommers since he looks the strongest or will it be killingham since his df ability is to manifest people's fears which seams to be an opposite to luffy's df or will it be someone else completely.

Edit: I think that shamrock will be the main villain in this arc and due to lack of tension or imminent threat more holy knights will be introduced in this arc to raise the tension