I'm going to be in the market for a new office chair pretty soon. I've been looking at the Herman Miller and Steelcase chairs, but I don't know. I want something BIFL.
I bought a Stressless recliner last year for my living room and I love it, so I've been checking out their line of office chairs. Cost seems in-line with their recliners, which is high (especially considering the office chairs do not come with an ottoman), but they are certainly BIFL quality and I can attest to their comfort and durability.
The Mayfair office chair (which would match my Mayfair recliner) is around $2600, while the Consul is around $1600, which is much more reasonable.
They may not be as ergonomic as the Aeron or Leap, but the comfort is certainly there as well as the quality. I don't know if the "real" office chairs have the same lifespan as the Stressless.