At the moment, I'd think about a 360/3-axis simulator, so I could rotate it into any position gravity made my body the happiest.

Combined with a large curved 4K screen and a split keyboard at each arm with a trackball/touchpad for cursor/gestures.

It's fun to think which seatbelts would be more appropriate for a programmers chair, but, in this case, I'd think they'd be a hard requirement.

What a good question.

I have a day chair, a chair for home, and a couch at home.

I'm a big fan of flipping between multiple chairs and taking breaks.

Very good question, I've been foam rolling my back per my Dr. of physical therapy which helps a ton with back pain.

This is my dream chair...

https://gravitonus.com/gravitonus/products/iclubby/

Wouldn't this depend on your particular configuration of muscle, bone, and fat?

Personal preference, activity level, desk type, and (dis)ability status would all be important factors, as well.

A squat rack.