I am really just learning how beautiful bettas can be.  I've seen pics of a beautiful white one, so I voted for white.  
Is there really a true black betta now?  I'd love to see a picture of it.  
Many years ago I used to buy fish from a breeder in a nearby town.  They raised angel fish and bettas and a few other things.  They had beautiful deep red and blue bettas, but the black betta remained their elusive dream.  
As time went by, I moved away from New York and when I returned they were gone.  I've often wondered what became of them and if they ever succeeded in developing a black strain.