well you have to take into account the actual power they posess as compared with the physical threat they pose....

from what we have seen so far kizaru should be the strongest of all physically speaking since he can presumably move at the speed of light... compare that to enel whos power is ligtening and specifically electricity... for a world who is coming into a modern era of science and such a man who effectivley can control ALL of this is a ery powerful foe indeed.... i have said it before its like magneto... physically hes weak but his power is to abuse the powers of man, same as enels was. IMHO thats why enel would have had such a high bounty... aokiji and kizaru would have wiped the floor with him and perhaps even someone like crocodile and moria would have also.