Years back I bought a used Herman Miller Aeron, it was way out of warranty but also way cheaper vs buying new. Totally worth it, I do like mesh chairs and the Aeron is one of the best in its class. Plus it has a ton of adjustable levers if that's your thing.
The only thing I screwed up was the sizing, those chairs come in different sizes and I probably should have gone for one size smaller but it's not a big deal. Sizing is something to keep in mind when chair shopping, they're not all one size fits all and you may want something specific to your height/weight for better support.
I had a chair with an extra sturdy (allegedly) textile for the seat and that still tore over the years from the friction. At least I can still sit on it but on a mesh chair that would be impossible. I'm just wondering if those ridiculously expensive ones have at least modularity & replacement parts, but if that's not the case then I see even less the point in them. Not that I could afford them either way, but at least then they would've made sense as something to possibly save up to, even if used.
I have an Aeron that I bought over 10? years ago and it’s still in great condition with daily usage. The only issue with it is that the fake leather type material on the arm rests has scrunched up and the texture is not so nice anymore. I could replace those if I wanted to though.
Lumbar support, height/back/armrest adjustment, headrest, right fit for your body. In other words, features that promote good posture, instead of slouching. Nowadays I find most ergonomic chairs have pretty much the same features, and what differentiates one from the other the most is quality. Aeron and Steelcase are basically BIFL chairs, whereas a cheap chair from Staples or Amazon may last you a year or two before things start falling off.
I have a Leap v1 from a surplus store, and a Mirra from when our company let the lease go on the building nobody went to anymore. Very much worth it on both fronts. A huge thing with "nicer" chairs is that they allow you to shift as you move throughout the day. A lot of people fixate on the "S" part of RSI and try to make sure everything is situated just so, but it's also important to work on the "R" and to move around, standing of course, but even just being able to move around and have multiple comfortable seating positions can be helpful.
Steelcase leap V2 is my suggestion, go sit in one whatever your choice get a bit of time in the chair make sure it's for you, is a investment and not a cheap purchase etc etc
These are what we have at work and they're fucking incredible. We work 12 hour shifts in a 24/7 operation and they've held up to this for over 10 years. I bet OP would never need to buy another office chair again. I think you can find them used for a more reasonable price from those places that sell used office furniture.
Can I please suggest gaming chairs should be a key player here? SecretLabs makes amazing chairs and I sit on one everyday. One of my female employees isn't too enthused about her's but she's the outlier. I also fully support/love the Hag Capisco. Have it as well and it is very very comfortable albeit a little tall on its shortest setting.
My secretlabs chair has a headrest, adjustable lumbar, height, lockable recline, armrest height and width and side to side. It might even have a forward and backward seat cushion but I haven't messed with that in awhile so I don't remember. I was very specific about this brand as an example and I think it competes very effectively with other quality office chairs. Your hyperbole is lost on me.
They completely replace the foam seat, so its really only the frame that was used. Significantly cheaper than buying new and safer than buying used from eBay/garage sale/etc.