hard one to answer, but I'd say earth bending, true fire bending is nice but earth is everywhere fire isn't, Water bending is Ti Chi wich you can find anywhere so where's the fun in that, Hungar and both Xaolin techniques are hard to come by so it makes those bending skill all the more rare and beautiful, but air and water bending dont seem to be quite as harmful as fire and earth bending so they're a bit too soft for me so earth bending seems to have the most pros which is down right sweet
Toph and the Earth benders rock!