Now for obvious reason I don't know what everyone else prefer in terms of finish color for their basses, but a big hint ought to be that most basses that are only offered in 2 colors, 1 of them will be a black finish, and the other usually either red or white, so I would think it is a pretty popular finish.
And my best guess is that the out of those more black basses are sold than the red or white ones.
As for my personal favorite finish is matte black, but I'll take a regular black one if it doesn't come in matte, which most basses doesn't.