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.