Ignoring the part of me that wishes all my electronics matched, I'd really like a black plastic that highlights in red, depending on the viewing angle and lighting, similar to how Xbox 1's plastic was not black but a tremendously deep green, if you looked at it right.
That being said, I'm extremely satisfied with what I have right now and would only consider special edition designs, like what they did with the NES and Pikachu GBA SP. (Yeah, yeah, decalgirl.)