Everybody's body is different. You've got to go and try them out.
I've got a Herman Miller Embody and Steelcase Leap: they are both great chairs, but neither is perfect. Embody has a completely fluid motion of the back, but it tilts the seat's front a bit too much up when leaning back (and it creaks a bit after couple of years). Steelcase Leap doesn't have the seat's front tilt problem, but the back doesn't move as nicely and setting up the tension is kinda hard to get right. It also has a more nicely padded seat, but it also gets much warmer.
Though I got Steelcase Leap last year because of the niggles with Embody, I still prefer Embody for daily sitting (not that Leap is bad, I am not bothered when I sit in it either, I just prefer the back movement of Embody, and reduced sweating too). I also like to combine it with standing at least for video calls.
Now, this is a perspective of a 6'5" (195cm), 97kg guy with a particular set of proportions and body weight distribution (and lumbar issues): nobody will have exactly the same experience with these chairs. Unfortunately, the best you can do is to get a chair and try sitting in it for a week: no sitting in the store and outside of your work environment will let you learn if it works for you or not (which is why I got the Leap outright).
If you are not in the 5% of the undersized or oversized people, and your limbs and torso proportions are close to average, any of the well-known and well-reviewed ergonomic chairs should do the job (Aeron's seat frame cut into my thighs, even in the largest C size, but obviously it works for most people).
There was a post on slashdot years ago where someone had built an office chair out of the driver's seat from some kind of mercedes that he pulled out of a junk yard. I've always wanted to try that, look for a car or suv with a comfy seat and build a desk chair around the seat
Edit, I looked for it and I can't find it. Does anyone else remember what I'm talking about?
I have one of those and an Embody. i'd spend more time in the stressless if its something im doing thats chill. the embody is more of a get shit done kind of feeling.
FWIW, most of those look terrible for anyone (significantly?) taller than average. Headrests are a big no-no for me because they cut into my upper back or shoulder blades, and integrated headrests into seat backs are even worse (this includes headrests on chairs like Leap, which is supposedly good for tall people).
Eg. check out the posture of the guy in the video under "Functions" for one of their chairs at around 00:16 in at https://shop.stressless.com/en/home-office/stressless-magic-... — that's not how you should be sitting with your chair making you slump your shoulders, and the guy doesn't even look particularly tall.
But this mostly illustrates the point that chair choices are a hugely individual matter.
I've got a Herman Miller Embody and Steelcase Leap: they are both great chairs, but neither is perfect. Embody has a completely fluid motion of the back, but it tilts the seat's front a bit too much up when leaning back (and it creaks a bit after couple of years). Steelcase Leap doesn't have the seat's front tilt problem, but the back doesn't move as nicely and setting up the tension is kinda hard to get right. It also has a more nicely padded seat, but it also gets much warmer.
Though I got Steelcase Leap last year because of the niggles with Embody, I still prefer Embody for daily sitting (not that Leap is bad, I am not bothered when I sit in it either, I just prefer the back movement of Embody, and reduced sweating too). I also like to combine it with standing at least for video calls.
Now, this is a perspective of a 6'5" (195cm), 97kg guy with a particular set of proportions and body weight distribution (and lumbar issues): nobody will have exactly the same experience with these chairs. Unfortunately, the best you can do is to get a chair and try sitting in it for a week: no sitting in the store and outside of your work environment will let you learn if it works for you or not (which is why I got the Leap outright).
If you are not in the 5% of the undersized or oversized people, and your limbs and torso proportions are close to average, any of the well-known and well-reviewed ergonomic chairs should do the job (Aeron's seat frame cut into my thighs, even in the largest C size, but obviously it works for most people).