Yes, this 99% has been posted before, but I don't wanna search for it.
Anyway, what franchise do you think would make a great game on the Vita. And would help the Vita's sales.
Mine would be:
Grand Theft Auto - we all know this is possible, we've seen the two great PSP games, if the PSP can do that, what can the Vita do?
God of War - just like GTA, we've seen two gruesome and beautiful PSP games, imagine that amount of blood on the Vita screen!
inFAMOUS - Uncharted and Resistance have seen the light of the day on the PSVita, but why hasn't inFAMOUS had a Vita game? Are Sucker Punch secretly working on one?
Borderlands - these games would look fantastic on the Vita's OLED screen and would feature Borderlands on the go (duh).
So far, these famous franchises have come to Vita.
Need for Speed
Call of Duty (a bad one)