It's neither Momousagi or Chaton. I don't Garp will accept the offer for Admiral, and Tsuru the same.

Out of the two, Momousagi will most likely get the postion.

Garp has canonicly declined the admarial position, cuz he does NOT want to serve under the WG

Garp’s retired, Tsuru is probably too old, and we have no info on the other two, so I’ll just guess the guy with the hat

Momousagi is a confirmed admiral candidate, so her

@IonShigiraki Chaton also is, and he has a hat. So clearly he’s better