MegaMan, but not for any of the protagonists, really. Unless you count ProtoMan.
I don't care if MM, Zero, Tron, or Roll ever see a game again (much less a crossover fighter). Give me some Storm Eagle, some Magma Dragoon, some PharaohMan, and some TopMan if for no other reason than his theme TO THIS DAY is still my favorite theme in the series.
NP: Borderlands 2, UMvC3 C. Viper/ Iron Man/ Sentinel, Felicia/ Sentinel/ Strider