The covers look a bit better on a black background
The colors are more vivid. This might give a better idea on how the actual single would look like when you hold it in your hands, since the printing quality would be good and you won't hold them against a white background.
Now we'll have to wait for the HQ pictures and we can really imagine what it'll be like
http://img515.imageshack.us/i/sunriseblack.jpg/