Agree! White would be good (depending on surrounding paint colors/decor). A more stylish look for painting fireplaces is a dark color. Black (matte finish of course) is kind of in and a tv mounted above would blend right in. I've also seen other moody colors look really good - like charcoals and other muddy colors. Depends on your style.

I think a gray like Marilyns dress from BM is a nice neutral gray and i have used it to paint those bricks it looks great.This is one of the times i would put the T.V there too maybe with a mantel deep enough to hold T.V. stuff you need

These are some of our projects that might help!

there is a gray in the marble but the paint for walls already chosen by the owner is more of an almond.
this is to be a rental home, also need suggestions for inexpensive flooring..laminate color

Are you able to change the black surround? I feel it might really pop too much with the stark contrast between the white and black. Otherwise, white will look nice with the marble.