my review of office chairs i've had:
some staples bullshit mesh task chair - sucks a ton of ass. fit doesn't feel right, back hurts every time.
ikea markus - good back/head support, well built. the seat is hard as a rock and is angled up which doesn't feel right and butt hurts within hours. sucks ass because of that.
hermon miller aeron - it doesn't feel like anything special at first but my back never hurts. butt never hurts as well. armrests annoy me but it's ok. don't feel the need for head support either.
verdict? aeron. it's expensive but if you buy used, you could sell it and not lose much if you don't like it. if you use it a few years you might only lose 100-200 bucks in value. but you're not going to sell it because it's that good.