Quality Polyurethane foam
The most important thing in the chair is quality foam. Many manufacturers are using cheap recycled foam that feels the same as quality polyurethane foam at the beginning but losses its comfort after half a year.
Fully adjustable chair
To make sure that chair fits each individual perfectly and allows him to sit in the perfect posture it needs to be as adjustable as possible. A perfect chair needs an adjustable backrest with tilt mechanism together with adjustable height and armrests.