Gamboa OF COURSE!
Gamboa can throw punches from crazy angles and his feet doesn't have to be planted for him to throw Power punches
2nd I would go with BERTO...NOT KHAN because Khan speed is mostly in his jab and his straights but Berto probably has the quickest uppercuts in boxing today, and like Gamboa and as shown in his last fight his feet doesn't have to be planted either to get off Power Punches