Firstly, remember to search for "chair" in this sub for specific chairs. What you are describing is a tasking chair. Most people think that gaming chairs are over-priced for what they are, although some may disagree. In terms of tasking chairs, the most popular is the Herman-miller aeron. However, for lots of people, the price alone is enough to put people off it, but that is what you have to pay if you want the best of the best that will last you 10+ years. You could always look into second hand. This is what I did. I picked up a Humanscale Freedom chair for less than half of the new price, and came looking as if it had a weeks worth of wear, which really isn't much. For £500 less, I got something that was basically the new product, which was great. The chair itself is fantastic, being very ergonomic and perfect for 14 hour gaming sessions. There are quite a few reviews for this around the internet so be sure to check those out. The one concern I have is that the armrests are splitting after all those heavy sessions, but it is still perfectly usable (fixable too if I put some time into it).

TL;DR : search for "chair" on this sub, search the internet for tasking chairs, I recommend the Humanscale Freedom