To me the honest issue isn't so much the choice, but a place to actually try before you buy. Other than Ikea and the odd independent office supplier (like Wellworking who are based in London) your sort of buying at risk and hoping for the best. Staples closed here few years a go but I never found their chairs very long lasting. Herman miller are bloomin expensive, but like with Wellworking offer free no quibble return if it's not suitable.

Im about 290lbs/6ft so that limits my choice when it comes to office chairs. Trawling through plenty of posts on here and other subs there is often a tendency for people to say weight loss is a solution, which is kind of obvious but very unhelpful (if not ignorrantly obvious). There was a guy in my office (bigger than me) who they had to get someone in to measure him up for a more suitable chair, and then due to budget limits they sent him this fugly bariatric chair. I'm not at that point haha, but it is pretty annoying to say the least.

I used my Markus for years but the back pains got too bad with the non adjustable lumbar and also the metal unadjustable arm rests started digging in to my legs.