I've broken a lot of chairs in the last decade. It comes partly from being extremely heavy (my skeleton was replaced with adamantium), and partly from forgetting that I am and sitting like an eight year old. And it can get pretty expensive replacing your office chair every few months.
My newest chair, by Global Industries, is just what I've been looking for. It's a bit pricey, but so far it's held up great. It has a high weight limit, a metal base, and most importantly, the arm rest are optional. This is a big deal. Most of the chairs out there use the arm rests to hold the chair together, so if you're large enough to push against them, it weakens the whole chair. Luckily I'm not too wode to use them, but if I were I could just take them off with no penalty.
I give this chair a five star rating.