I like my screen to be dim, and find that the white parts of an LCD are usually too bright, even when the brightness is turned right down. I expect an off-white or grey background on an OLED screen would be better, but they haven't made their way to the desktop yet.
On my phone with an OLED screen I still prefer white-on-black, but that's mainly because even at the lowest brightness it is still far too bright at night.
On my phone with an OLED screen I still prefer white-on-black, but that's mainly because even at the lowest brightness it is still far too bright at night.