Technically you can also fly using water/earth via flying atop large chunks of ice/earth. Heck you can even fly Iceman style depending on the water/ice generation style of the water bender. You can even fly with firebending by using your fire as jet propulsion for your flying.
Curiously, if you had to vote which element would get lightning/electricity manipulation, which would it be? In the Avatar universe firebenders are given that ability, but in most other media, lighting/electricity manipulation tends to go towards air/water benders.
In any case I vote vote water.