There's no question in my mind that a lot of studio still work looks more dramatic, on the net, with a black background, but...
a lot of perusing the "for sale" artistic websites tells me that black isn't a popular background for the type of stuff that I cough out.
As I have been working with smoke of late, I offer this as a case in point...called The Valkyrie and her Pet.
With the exception of manipulation, the smoke on black is SOOC followed by an inverted image.
In your humble opinion...which might be more saleable at the local Art Show? FYI...it is 40" wide @ 300ppi.