Try the Herman Miller Mirra, it's a lower chair in their line but the back structure makes it far superior to the Aeron.
I now work from home and think it was one of the best investments I've made in myself. The chair is very comfortable and they adjust very well for tall or very short people (my wife).
Rating: Would buy again
Can you compare it to any other chairs? Most of us (myself included, with the Aeron) love their first ergo-chair, making it hard to compare them. :-)