Richard would surely roll his eyes at it, but I bought an Aeron knock-off at Office Depot about 5 years ago and its been the best task chair I’ve ever used. The originals are probably way nicer but I’ll never know. I can’t justify that kind of money for a chair and buying a used one, for me, is like buying used shoes. Its not necessarily great looking but is thoroughly adjustable.
https://www.amazon.com/WorkPro-Quantum-Ergonomic-Mid-Back-Chair/dp/B007OZX9DO/ref=cm_cr_arp_d_product_top?ie=UTF8