12Guardians of the Galaxy
Admittedly, this one is highly unlikely, due to the fact that Marvel/Disney currently owns the Guardians of the Galaxy, and Fox owns the X-Men. Still, it would be pretty amazing to see the X-Men meet up with Peter Quill and the gang in outer space – not
only are the Guardians an amazing team (and their movie was a huge hit), but a team up movie would be a nice change of pace.
In general, the next time the X-Men go up against a villain, seeing them co-operating with another team (and potentially struggling to do so) would be something truly different. On top of which, we just want to see as much of Star-Lord, Groot, Rocket, Drax, and Gamora as we can!