I ditched regular desk chairs for an Ikea Poäng many years ago. But then one day I realized that the Poäng was giving me lower back pain, so I ditched it. Now I sit on the footstool that came with the Poäng. (for the past 4 years now, I'll do cross-leg, squat, any kind of sit you could do on a floor)

My keyboard is an ErgoDox EZ with the lightest key-switches I could find (bought them separate, soldered them on), and my mouse is placed in the middle. I'm happy with other keyboards though, my general keyboard requirements are:

* ortholinear

* as many modifier keys on the inside as possible (eg CTRL/SUPER/SHIFT for pointer and thumb, instead of using pinky)

* split layout

I use a 3M adjustable keyboard tray (atk91le) screwed into my desk so I can easily adjust position for whatever posture I'm in.

If you sit too long without moving you will hurt, so I make a point to switch up how I sit, or get up from my desk frequently. I really like the footstool as a chair because it's like an elevated floor, there are many ways to sit on it.

If my lower back is tired (no backrest on a footstool), I have a Nada Chair that I'll sometimes strap into.

I have scoliosis, so I think I've had to deal with lower back pain much more than the average person my age.