ergonomic chairs is the way to go, stuff like:
- Herman Miller aeron id you dont have a giant ass
- Herman Miller embody
- steelcase leap V2
- haworth zody (i have this one)
are one of the best chairs ive had pleasure to test out
these chairs are pricey and new they xost at least 800 EUR each but you can get used or refurbished ones for 1/3 to half price, i highly recommend checking sites like craigslist in your country (its olx.pl in Poland for instance)
they have a lot of ways for adjustment like how far from the back you put your ass on it, how far can the back sway or how much pressure do you have to put into backrest to start swaying back or event a sit place single in some cases, many of them also have lumbar support and i don't mean these SHIT pouches you can find on all "racing" or "gaming" chairs but an actual support which is adjustable by moving a bar up and down or even in haworth chairs you can set different pressure on left side than the right side of your lumbar
even if you get a good chairs, you if you will sit like a goblin on them then this entire research will be kinda useless; to you should ensure you sit in an ergonomic setting like having your screen not too high, not too low just on the same level your eyes are, not too close etc etc you can google this out
a good way to find out what fits you is to go to resellers and just ask them if you can sit on them for like idk 20 mina do you can see how it goes; you don't have to buy it from them later as you assess what is the best for you and it can always be like you will never buy it from any reseller sińce you will buy used but they do not have to know it, that's what i did ;) but i ended up buying new because i got 12 years warranty for the chair and that seemed to be a great deal, cuz even if anything breaka they will send me a replacement part
with used/refurbs you have no warranty, also some companies literally void your warranty like haworth if you are a seconda hand user