Imu is #1, but it just goes to show how strong Cobra's haki is! /s
Have we learned nothing from Bleach's Chair-sama?
Oda's way of showing how quick Sabo is, is to have him run away at super speed. Same for Wapol, there's hidden potential that only now was put on display by showcasing how fast he can run from CP0. Wapol is faster than CP0, imagine that!