re: Seeking Chair Recs
@cephie Don't know if you're still looking, but I have an IKEA MARKUS chair and it ticks all of the boxes; I would say that it's the most comfortable such chair I've used (although imperfect), and after many years of use the padding has still not worn out. I'd actually say that the seat padding is a bit much sometimes, but not problematically so.
The standard casters suck; I replaced them with inline-skate-style casters a long time ago (note that these are third-party, and IKEA chairs have a non-standard stem size, so you need an IKEA-specific type). Though when the first set broke, they did replace the chair for me without complaint.
My main criticism would be that the (multi-point) seat recline locking mechanism is a bit janky; it loses accuracy over the years, and has a tendency to tilt the backside slightly in one direction when locked. I don't think most people would notice but I'm very fussy about that sort of thing :p