I'm apparently somewhat odd. I spend most of my sitting time at the computer in a simple, old wooden rocker. I've got a photo of my Mom sitting on it with my older sister in 1941, and I think my folks bought it used. So is there a prize for "oldest chair"?
It's a plain as can be - small, straight back, no arms. I've got some Walmart cushions on it. I like to rock backwards and get the chair seat to a reasonable slope.
For reading or watching TV, we have another, similar rocker that we bought for my wife when our DD was born in 1976. It's smaller than most modern rockers, but it does have arms. Again, simple cushions. I'm the only one who uses it these days, my wife uses a hard wood kitchen chair.
When I was w*king, I sat on in the same chair for 25 years. Moved between two buildings, multiple cubes and offices, but always took the chair with. It doesn't meet modern ergonomic standards, they probably trashed it when I left. I would have loved to have bought it from my employer on the way out the door. But, mega-corp red tape made that impossible ( now I remember why I wanted to leave).