I don't know how quickly the game is going to ramp up in difficulty, but I imagine my L30 monk is going to be using a lot of Deadly Reach with the Piercing Trident rune. The range and aoe on that was very substantial compared to any of the other generators. But I'd guess that by L60 you'll be much more concerned with generating lots of spirit for other abilities than with doing lots of damage with the generator.