Hermon Miller Aeron and Steelcase Leap V2 are the go to chairs but cost $$$$ you can find them cheaper when offices decide to replace everything.

All of the parts can be bought from the manufacturers and be replaced generally. They also have a focus on adjustability and ergonomics being designed to be sat in for 8+ hours a day. Usually have 10year or more warrentys

If you dont want to fuss with maintenence save some money and go with fabric instead of leather.

And of course try and sit in one somewhere before you buy it.

I also like the ObusForme chairs - they are 500-1000 depending on the model, but last years. If you order it, you can pick the color/fabric.