Really, I don't think there is any one answer to this particular problem. Personally, white text on a black background makes my eyes get all wonky, so I usually code in a white background with color-coded code. In a terminal session, I usually use a muted green on black, as the green doesn't make my eyes bug out. But plenty of other people seem to have no problem with white text on a black background, and even prefer it. So basically, try a few and see what works best for you.