So the only one of these chairs my hind quarters has actually had the pleasure sitting in is the Aeron chair and folks it was a metaphysical experience.
According to U.S. Ergonomics, here are the top chairs for comfort and health:
#1: Steelcase Leap, $850Also on the list (in no order):
2. Freedom by Humanscale, $1305
3. Acuity by Allsteel, $1250 (covered here by Unpluggd)
4. Life by Knoll, $1240
5. Aeron by Herman Miller, $930
6. Zody by Haworth, $880 (featured here on Re-Nest)
Ubertechnica 
I agree with you that the Aeron is the best ergonomic chair. Until now, this seat still lead the market. It is the very comfortable chair, although it is expensive. But, we will get warranty for 12 years. We get free repairing if there is a part of seat broken.
I love my my Aeron chair – second best productivity device I have!
I actually prefer my Flash Furniture executive high back chair. Pretty cheap and quite adjustable. Though according to http://mycomputergamingchair.com (is this a legit site?) that DXRacer “gaming chairs” are the best chairs in the market today. What do you think?