first of all, it depends on if you jump seat in or seat out. for seat out, most riders will agree that a relatively high seat will be better for hopping high. for seat in, most riders will agree that a relatively low seat will be better for hopping high.
you really should just experiment and see the pros and cons of riding with different height seats.
i have mine as high as it will go, but since im 6 foot and riding on a Koxx Reinforced its pretty damn low, maybe 3-6 inches under hips
typically freestyle is the highest followed by trials, and street/freestyle.
personally i ride a high seat and i do everything on it. my muni i ride lower (in comparison) but not low.
typically you can jump higher with a high seat SIF, and a low seat SI.
i jump higher with a high seat period. might be because that is the only way i have riden for the last 6 months+
I ride my seat at my belly button.
Totally and completely depends on what you like best…in general, most street riders have theirs rather low, but look at Dan Doerksen, he was really good at street but had a super high seat (rhyme).
Freestyle riders generally have a higher seat…and distance riders too. One could actually argue that higher seats are indeed better for distance riding, but that’s about the only type of riding when there’s an absolute best. The rest is just personal preference…so in conclusion, figure it out for yourself!
I seem to like at the waist for all around, but I ride only 24".