Well, I'll take the dissenting view here. Some styles are developed for specific body types and to utilize their strengths. The systems developed for larger, stronger fighters are more powerful in a generic sense.
Now wait a minute guys! Before you jump on me about this first let me say that I agree that you must find the system best for you and develop your power and abilities as best you can.
However, some systems inherently have "power" as their focus rather than speed, accuracy, redirection, or any of a hundred other possible areas. For example, there are nine primary animal systems in Bando as taught by the American Bando Association. Hands down, the Bull form is the most powerful. No contest. Does that mean a Bull practitioner is more powerful than me? No, but it means he has the potential to be, cause Bulls are bigger and stronger than me. In fact, each animal style was developed for specific body / ability types so as to maximise their potential, but everybody knows better than to stand toe to toe with a Bull or Boar.
Now some will say, "But if you train harder and use your speed, you will have more power!" True, but that's not what was asked here. The Cobra (speed and accuracy attacking vital targets) can beat the Bull, but not by brute force, which is what I think was meant here.