I like Hercules office chairs. They're meant to hold 300lb people for 8 hours a day. I'm not that big, and I don't sit that long, but the chair has lasted me a lot longer than cheap or even moderately priced office chairs.
I've never tried those expensive Herman Miller ones though. That's just too outside my budget and mesh doesn't look very comfortable to me. Not too mention my cats would shred that up.