DISCLAIMER: I'm not any kind of technophile, so maybe it's not strictly midi music, but I'm basically talking about the cheap, tinny sounding music you'd get from 16-bit consoles. I'm sure it's been done before but I'm in the mood.
I love the nyan cat music so much.
Something about that stormy bass in the background and the ecstatic, addictive melody just gives me the shivers.
This is another song that is better than anything on OK Computer or Loveless - the Streets of Rage 2 ending theme:
I'd honestly say that right there is one of my favourite pieces of music.