Desk Chair Recommendation?

I’ve been using the same el-cheapo Office Depot desk chair (similar to this one) for about 6-7 years now, maybe a little longer. It was fine when I was working at a BigCo and only occasionally doing work at home, but now that I’m working from it 40-70 hours a week, I’d like to get a chair that is a little more comfortable and better for my back.

I used an Aeron chair for a few years at the BigCo but was never a big enough fan to justify the price. I’ve also looked at little at the Relax the Back store – very expensive but comfortable stuff. The foot rest seems like a good investment.

I’ve also considered a kneeling chair – my mom used one of these for years and really liked it.

What kind of chair do you use? Do you recommend it? What are some things you would look for/avoid if you were choosing a new chair?