And I say water because: can be liquid, can be solid, can be made from your own sweat or out the air, and well blood bending
Air bending is 2nd cuz it’s hella abundant, people are less used to fighting air benders cuz there’s less of them, and you can take the literal air out someone’s lungs
Earth is 3rd mostly because of lava and metal bending
Fire is last because even with lightning bending I don’t feel it’s as destructive on a massive scale compared to the other types