I had the same need after using for the past 12 years an Ikea Makus at home; it is fine for shot term use, but not for 10-12 hours a day. I recently managed to buy a second hand office chair from a local office that was selling their old chairs; I don't remember the brand, I know that I searched it on Internet and I found nothing, but a few years ago I was using that model of chair for more than 12 hours a day and it was extremely comfortable. The info from the office management guys is that model of chairs is not sold to end-users, only in bulk to companies (minimum order over 50 pcs) and the price was around 600 EUR ($650), that is more than the average net monthly salary in the country.
I heard many people talking about Herman Miller Aeron, but the price is high and availability low here, so for $100 I am happy with my purchase. I definitely don't recommend any Ikea chair, we had several in my family and none is good enough.
Another thing that I saw it works very well with any chair is standing as often as possible; every time I am in a meeting I stand and walk around in my home office while I am talking, while doing desk work I stand and take a walk to grab a tea or water every hour even if I am not thirsty; that minute or two helps.
I heard many people talking about Herman Miller Aeron, but the price is high and availability low here, so for $100 I am happy with my purchase. I definitely don't recommend any Ikea chair, we had several in my family and none is good enough.
Another thing that I saw it works very well with any chair is standing as often as possible; every time I am in a meeting I stand and walk around in my home office while I am talking, while doing desk work I stand and take a walk to grab a tea or water every hour even if I am not thirsty; that minute or two helps.