Although I really like the idea of the Zombie Gameboy a little more (the monochrome sprite for a face was a brilliant touch), I think I had to choose this one as a favourite. The colours on the wires come through better (in this photo, at least) and the feet on this one make it easier to imagine how it could shamble about.
These are relatively small aesthetic elements but they make them distinguishable enough.
In any case, I'd like to say you've done great work with both of them.
I want soooo badly to congratulate you on your DD!!!! But this poor system... what have you done to it!?!?!? That is seriously one of the coolest things I have seen in a long while, but I still feel so sorry for it.