I think I'm in the minority, but I prefer to sit in a plain wooden chair, of the standard-issue kitchen table variety.
It's essentially a hard wood platform, so I sit upright while typing and seldom find myself slouching backward. That seems to do nice things for my posture. Nothing ever gets tired/strained/injured, even though I've been working this way for several years (and I'm 42, so if health problems were to be had, I'd have them).
Back in my cubicle days, I'd spend my time slouched back in the Aeron, with terrible posture all day. My butt would get sore because it was being used as a scootch-guard to keep me from sliding onto the floor. That doesn't happen anymore.
Around the same time, I started making a point of never reclining my seat on airplanes. Long flights used to be a giant butt-ache from the 2hr mark onward. Now, sitting upright like a human being, I'm good to go for 14hrs and beyond. Even sleeping comfortably with everything balanced on top of my spine.
Sitting up straight. It's the way forward.