Hermann-Miller has two lines of ergonomic office chairs that have both worked very well for me for many years. Aeron chair ($1,100 to $1,500 depending on how it is configured) and the Mirra 2 for a couple of hundred less again depending on the specific configuration. Very expensive and IMHO worth very penny especially if you have back pain issues.
I spent a lot of time researching last fall. I have a Steelcase Amia, a step down from their popular, more expensive Leap. One problem is that the lumbar bar (a horizontal bar that slides vertically at the back of the chair) doesn't slide down low enough for me. It seems built for taller people. I don't see what the big deal is about this chair. The cushion isn't even that comfortable and I get hot sitting in it. $600. Why? It's plastic.
Try a Google search for "adjustable height computer table"
Good idea.
