What office chair do you use for long hour sitting behind computer?

For long hours of serious work it's important to prioritize seating that provides sufficient support and structure to remain comfortable after several hours over chairs that may feel super "comfy" in the first hour. In my experience, they rarely overlap. Another important trait is durability and repairability (including parts availability).

My goto chair is the legendary Herman Miller Aeron. I've had my primary Aeron for >15 years and it still looks new, relatively inexpensive parts remain readily available on eBay and are easily user serviceable with a hex wrench. Aerons are built like tanks. They aren't cheap but no really high-quality, durable chair is cheap. The good news is that used Aerons are widely available.

A relatively newer chair that I'm using at my vacation house office is the Steelcase Gesture and I'm really liking it. IMHO, its best feature is the infinite adjustability of armrest position which is by far the best I've ever seen. However, the long-term comfort of the chair itself apparently varies by individual. I love it but I've read that, unlike the near-universally beloved Aeron, the Gesture just doesn't click with some people so be sure to give it a test drive first.

No chair. If its 3PM, I'll sit down for 30 minutes and take a nap. Then I'm good for another 2.5-3 hours of computer work -- standing.

https://www.amazon.com/s?k=kneeling+chair

Kneeling chairs aid in keeping natural posture of spine.

IKEA Markus Chair: It used to be the WireCutter's (budget?) pick for several years. I thought only the leather version had a 10 year warranty, but it seems all models are protected for 10 years, now. And less than $300.

I sit at my computer way too much, but I've never had problems with my back/neck like other people. It may be the way I sit: "leaning/slumping" back into my chair. (Most people seem to hunch forward).

If you want to go for cheaper (ish), when I read up on chairs the ones from Sealy (the bed people) got good reviews, and I got one. It's very soft and comfy, and my children try to steal it.

Secretlab chair at home. Steelcase leap at the office.

Steelcase Gesture.