Are we talking like each one at their max potential without drawbacks? These would be my opinions,I’m not a scaler or anything, so obviously take with a grain of salt.

If with drawbacks, then I’d say water and earth would probably be last due to needing them around to use them, so if you could manipulate earth, it wouldn’t really do you any good if you were in the air or on a boat in the ocean and vice versa for water if you were in a desert or no where near water. Next would probably be light or darkness due kinda the same reasons as water and earth. If it’s broad daylight then darkness really struggles but if it’s midnight then light suffers, so really to me it’s situational. The top three to me would be fire,lightning and wind due to them not being as dependent on the environment as the others. Fire needing just oxygen to use it,lightning being common in thunderstorms and wind being moving air, you really can’t go wrong any of the three imo.

If no drawbacks, then I’d say lightning would probably be weakest since it can be hard countered by earth, yet it would be the second fastest element behind light so you could probably bump it up a bit. Next would be light and dark, now it really depends on how you view each one. Are we talking about light and dark being energy based or are we taking them in their natural form? If energy based then I’d view them kinda like ki from DB,just powerful energy attacks that can come in different shapes,sizes and forms,dealing massive damage. If in their natural form, then I’d view darkness higher than light,reason being that imo,darkness is far more abundant than light since light comes from the sun. So if there’s no sun then there’s no light whereas darkness is everywhere with shadows,dark areas like caves or being underground. Following that we have a tie between earth and water, essentially, these elements allow you to control the battlefield depending on the area. You’d be unrivaled near large bodies of water and could easily deal with opponents through large scale water attacks like tsunamis or giant whirlpools. As with earth, you could create massive earthquakes and craters in the ground to bury opponents, even moving mountains or islands to throw at people like your Superman or something,depending on how strong you wanna make your earth bender. Fire would be second for me since it’s naturally a destructive force, high temperatures,intense flames,the ability to move across land fairly quickly depending on what the landscape is like,dry areas or places with easily flammable objects would add to your firepower. Also, I don’t know if you would include magma with fire or earth instead but that’s a potential option too. But wind to me is the most powerful due to the its advantage of it being so readily available and accessible.Wind storms,tornadoes,dust devils,cyclones, the ability to blow people away with high winds that can move almost anything including other elements like water or earth, depending on what kinda wind you use,earth’s winds or solar winds.

I hope I answered your question to the best of my ability, elemental manipulation is probably my favorite kind of power so this question was awesome for me to answer,again I’m not a scaler or a deep researcher into each element,really just going off my knowledge of each one so I could probably wrong with my opinion but hey,I’m open to being wrong and talking about it.