Yep, depends on the fish you keep and the type of decor you have, dark color fish will look great on lighter/white substrate and/or light white decor (like holey rock), lighter color fish will look good on darker substrate and/or darker decor (like slate/dark marble/granite etc..).
I like both looks, dark and light...I use crushed coral myself and don't find that the fish are pallid against it - a black background helps in this regard.