What's the most comfortable office chair you've ever had the pleasure of sitting in?

I end up sitting in front of a computer 12 hours or more most days and for the last 3 years I’ve been sitting in something about like this.

It’s lightweight, moves easily, and I don’t hate it.

But I started thinking about how much time I spend in it and it’s probably not the best choice for my body. I’ve experimented some with standing up while I work and will probably do more of that, but standing all day every day probably isn’t the solution either.

So I need to find a new chair. I’ve actually purchased one that was comfortable in the store but miserable after 3–4 hours in it and I’m not sure where to look next.

So, dear Jellies, what’s your favorite office chair?