For many years, I have used yellow text on a blue background. The rationale is that the human eye is least sensitive to blue, and most sensitive to an orangey-

For many years, I have used yellow text on a blue background. The rationale is that the human eye is least sensitive to blue, and most sensitive to an orangey-yellow, and thus this combination is the easiest for your eyes to distinguish. I pair that with xterm and the traditional 6x13 fixed font. But don't let that undermine the colour argument :-)