same here...had blue since 1991...switched to black 2 years ago when I upgraded... definitely prefer the blackI had blue on my last tank. To me it looked too much like a fish store holding tank, so for my new build I went black. It's personal preference really.
Generally speaking, a background which gives a sense of depth is the best. For example, a white background (a few inches away from the tank) with a soft blue light scattered above and behind the tank will give the illusion of infinite depth. You will, obviously, need to keep the glass clean.