With the new rules and everything that have gone around, personally a waterfall (or pancake as some call it) is more difficult and has a nice visual if executed properly. But on the other hand, if your full downs or (1 1/2 to flatback that is newly legal) has great technique such as straight legs, hips in line with the rest of the body and nice hollow position, it's not a bad decision also. now as for regular stunting difficulty, lo hi tick tocks, full ups/1 1/2 ups (not crossed legged) are some skills that will get you in the high scoring range. along with lo hi full arounds and unique inversions. Hope this helps!