When I was last shopping for a chair, a "gamer" chair was, by far, the best chair that I could find for my size (average height, but stocky and overweight). None of the chairs at my local office store went up far enough for my knees and the arm rests did not support my elbows at table level.

I am sure that their are high end office chairs that would fit me, but I did not want to do much research. I had just read a good overview of gaming chairs from Ars Technica and just went off of that.

Every chair I have had at work has the same problem. At one job, they had ergonomics experts come in to help set up our desks at a new office. The expert sat me down, fiddled with my chair, and apologized because it was hopeless.