I like some things full-screen, like my browser, but vim (ok technically full-screen itself, but split) always 2-3, probably most other things 2 side by side.
But I don't have a square monitor (I think it's 16:9) I don't see why that would be an improvement. If anything surely we want it wider for side by side use, so more 'lanes' can fit?
Give me as wide as they come!