What's your favorite color,
BLACK or
BLUE ?
That's what it comes down to, not what anyone else thinks. However, to answer your question...
I'm partial to blue in a
SW tank because if you have ever SCUBA dove or snorkeled you'd find out that the back drop of the surrounding water is blue. Below is an underwater photo I borrowed from the RC thread of the month. Two divers from Australia have a long post with over 500 underwater photos. Rob, our fearless leader, has a link to it somewhere on TR.
This photo is one of many that illustrates my point. But, if your favorite color is black then it doesn't matter what color is my favorite.
Dick