Here's what I use. I'm on my third one over about 30 years. Has rollers, you don't have to carry it. Fairly light weight, totally height-adjustable.
It can double as a dolly in a pinch.
http://www.officedepot.com/a/products/49...cF63hoC6KLw_wcB

Really nice but hard to move

Honest;y I use whatever they have at the gig....

I like to be high enough to be comfortable on the top board of a 2-board stack, so this is my stool of choice: Gibraltar GGS10T drum throne . I love how easily it folds up for carrying around.

Their description is a bit misleading --- 27" is not the height of the stool but rather the length of the center post (not very useful information for anyone but the manufacturer). The actual height of the stool is 30", so it took some work with a hacksaw to bring it down to a useable height. (They do also list what they call a 21" stool --- which probably means it's a reasonable 24" high to begin with.)

- Jimbo

I have a SoundSeat http://www.soundseat.com/ It isn't cheap but it is perfect for sitting at a keyboard. It is built for musicians and designed by a musician, is comfortable and is made to last forever. It is the last seat I will ever need. It is made with quality leather not vinyl.

Yes, thanks hammer, this looks like the seat i have been looking for... With the backrest...