As a timpanist, I've found numerous examples of different ensembles with a variety of timpanists; many play while standing, but I've also found that a majority perform while seated on a throne.

When I play, I feel much more in control when I'm standing. I can tune the pedal exactly where I want it; the seat makes me feel a little less certain as to how precisely I can set the pedal. When on the throne, it feels like more is up to the whim of the swivel on the chair rather than the concrete solidity of my feet. When I'm tuning one drum while playing another, I feel that keeping a solid foot on the ground allows me to maintain a certain sovereignty in my technique. When playing seated, it takes a little bit more of a balancing act for me to keep my playing consistent.

I was just wondering as to who prefers what and why.

I prefer sitting down. If you're taller than most, sitting helps improve your technique (better playing area on the mallets). Also, in some more challenging music, you might need to tune more than one drum while still playing. That might be hard to do, unless, of course, you can float.

I never really had the chance to play timpani in school, but generally whoever was playing sat on this tallish stool that we had in the band room.

I mostly prefer standing, but if the piece dictates, I'll sit down.

Definitely sitting. When you're standing, there's not really a guarantee that your hands are at a consistent height (because most people are taller than they need to be to play timpani, so they end up having to crouch or lean some). Also, with standing, there's the issue of pedalling the timpani mid-passage, or pedalling more than one drum at once. People that normally stand will sit when playing something like Bartok Concerto for Orchestra where you have to have both feet to tune, but to me, that doesn't make sense, because then you're likely to have an entirely different sound when seated than you would when standing. However, when I'm sitting I'm not usually putting my entire weight on the stool with my feet on whatever sort of footrest the stool has; most often I'm sitting far forward on the stool with my feet still on the floor, or my feet are resting on the pedals (of course, if you play balanced action this is a problem, but if you're on Dresden pedals it's not).

There are, of course, fine players that play both ways, but I personally prefer sitting.

I prefer to sit. In the ensembles I've played in, I usually get parts where I'm constantly changing pitch (and they're often impossible to accomplish while standing). Plus, I'm taller, so it's easier for me to maintain good technique while sitting.

sitting seems much easier to change pitch, but for those who switch instruments a lot during the concert season in high schools standing seems to be the first natural thing to do- although not as beneficial (IMO). I also think it's easier to sit for playing technique wise.

I prefer to stand.

maybe it's just because I'm not used to sitting, but when I do, I always hit the rim.
and it's easier for me to move around while standing.

i think sitting is much easire because when you are standing you cant tune 2 timpani at once. also if you are a taller person it might be uncomfortable to be reaching down so far to play those long rolls.

I vote standing. I like movement.