I'd like to dis-recommend Herman Miller for ergonomics. I bought an Embody chair a few years ago and the adjustments suck. The Aeron is not much better. They are both comfortable chairs, but they don't really conform to your body the way the marketing literature wants to convince you that they do. (The major problem with the Embody is that the arm rests tilt when you lean back, meaning that they need to be readjusted if you lean back. And the adjustments are in like 6 inch steps, so the adjustment is never very good. The lumbar support is also garbage. The rest of the chair is very durable and comfortable, however.)

Ultimately, you pay a lot of money for Herman Miller products that could be spent on better ergonomic features instead.

At work I have a Teknion Contessa and I love it. It is infinitely adjustable and very comfortable. I hardly ever think about my chair while at work. The only problem is that the fabric is not very durable; mine is a year old and it looks just awful. My Embody is much older and looks almost brand new.