BB look alright, but nothing looks as good as a well planted aquarium..
I had a plain 6ft tank no rocks/sand/wood nothing, this was because it a hell of a lot easier to do changes and clean up the glass, you dont have to bother with gravel snakes and cleaning out rocks.. re-planting etc.. for large, aggressive/semi- aggressive fish I personally would suggest bb.. but for more impressive fish, black is the way to go! Black background, black sand/gravel! Looks hot!
Its all personal if you want your fish to stand out, put nothing in there, your eyes totally focus on the fish!
Also some fish move gravel and up root plants, can hurt them selves on wood / drift wood, annihilate plants (waste of money) and if a fish gets some rocks down its gills that totally blows!
Its up to you! What are you planning on keeping?