I find that trying the chairs out - sitting in them for a while in various positions and working the controls - is the best way to find out what is the most comfortable.
People are built differently. I tried out a chair that the owner swore was the most comfortable and adjustable, and I was in agony sitting in it. There was no way to adjust it to make it comfortable for me. Seat curvature makes a HUGE difference in comfort, and that is virtually unadjustable in any chair.
You might try your local office furniture/machine/supply stores and see what they have and try them out. Preferably a store with good on the floor customer service.
Orange Blossom