"Cruel Clocks" by Hatsune Miku would be interesting. From what I've read so far, even the community isn't completely sure about the story or meaning of this song. So I think it'd be nice if CON clears it up. Or maybe it's just because I'm a huge fan of Drama and Romance and that would definitely be both of them..
"Kunoichi Demo koi ga shitai" by Hatsune Miku and Kagamine Rin would be interesting as well. I think it has more space for genres. It could be Romance, Comedy, Slice of Life.. In my Imagination it maybe has a story that is a little bit confusing, has always Cliffhangers at the end of an episode, and would end sad. Always with some funny jokes (except for the end of course, that would definitely ruin the mood).
And something I really want to see NEVER is "I'm sorry, I'm sorry" by Hatsune Miku.. Just.. no. If you know the song/the meaning, you understand why.. ;_;