I guess no chair can help me solve my problem, which is I slump. No matter what chair I sit in, I slump. I've reached the point now where my back is giving me problems, and I only realise I'm slumping in the chair when it begins to hurt.
(1) Exercise more. Many people have reported feeling a lot better once they just started exercising and strengthening up their muscles (back muscles in particular).
(2) Get a height-adjustable desk and spend part of the day standing.
I watched my dad suffer through severe back pain when I was younger. He had to have surgery twice. His was caused by football most likely, but still, what I can tell you is you don't want to let this grow into a legitimate back problem. I've witnessed the impact it can have. It's not something to be trifled with.