A rolling office chair with a good back support. I've used one for years. Tried one with arms but that didn't work at all. One of the reasons I like them is that the height of the chair is adjustable so that you can get it set to a level that doesn't work on your back so much. For me, higher is better. The other thing that helps with the back issue is a quick stretch every 30 minutes or so. Take two minutes and go through a series of the same stretches you'd use to warm up for exercise. You'll be amazed how much difference this makes.