I prefer to shop at an actual furniture store that carries high end furniture even if it means I pay a little more. Take the time to sit in chairs. Then go back and try again, with one or two people to try as well. Once you’ve decided on chairs most will require upholstery selection,then wait for orders chairs to arrive. An experienced salesperson at such a store is invaluable. I hope you live near a place that has such a store. Don’t overlook privately owned furniture stores in smaller towns. I am fortunate to have such a place (and more) in the area where I live. Once new chairs arrive your current ones could be sold or donated.

100% agree with the above. If you want comfortable seating, for your body, then you need to test the chairs at a local furniture showroom.