Black, it easier to keep clean, as for fish coloring, well it tended to make my guys whole bodies darker... sometimes that is what you want sometimes not. You can make that decision.
This is my ultimate decision as well. Heres my collection of photos from this site which make me think hard about both. The white/red/green is FABULOUS. But the black/green/driftwood is KILLER as well. I have that ocean look with white sand in my mind, and the black that would make ONE HELL of a color popper.
Heres my calab of all the photos I collected. The last one is nice to