When I started university in 1981, I wrote all my papers and assignments either by hand or on a typewriter. By the time I finished grad school, I was using Microsoft Word on a Mac Plus. I liked being able to easily make changes to the doc, but I found one huge negative: with the word processor I couldn't see as much of the document while I was writing. With paper, I could set several pages on the desk and refer to them frequently with quick glances. With the word processor, I could see only a few paragraphs and switching between pages was distracting.

I noticed that this had a big effect on the flow of documents I wrote. I found it was much more difficult to construct a long chain of reasoning without being able to easily review at a glance what I had previously written. Same applies when writing software: it's a lot easier to write coherent code if you can see more context.

Displays eventually got better, but in my view, 1600x1200 is just barely tolerable. 1920x1200 is a big step up when writing text, since it nearly two full pages can be put on the screen, but displaying three or four pages would make a huge difference and is really what I want.

1920x1080 isn't the same thing at all: the 1080 vertical pixels just aren't enough to display a full page vertically. I would much rather work on a 1600x1200 monitor than 1920x1080.

I'll second this suggestion.

The kneeling chairs break, at least the cheap ones do, with potentially very bad consequences. I've only broken one, but I know a guy who went through three. And even when they don't break, they put a lot of strain on the knees. I could never use one for more than half a day.

The exercise balls are surprisingly comfortable. You can learn to slouch on them, but I find I'm much less likely to slouch when using the ball.

Having your monitor and keyboard at the right height is probably as important as the choice of chair. I'm fairly tall with a long back, and I find I slouch a lot less if I can get my monitor up near my eye level.