GIRL HERE! I personally find water pretty useless as you actually need water to bend. My next least favorite is air. It's basically just making wind and stuff. Then earth, which would be pretty cool but then again, you do sorta need earth. And then you just make this huge hole in the ground and ya. my favorite is fire because all you need is the moves. Plus, fire is extremely powerful.
I love earth because if I did, I would make my brother stand of the side walk and then earth bend a piece of rock up underneath him and then bring him to thin air. When I am done with that I will bring him back down and when he is back he is knocked out. Hehe