Current list of great titles that would make great Stern pinball machines from this current thread:
Guardians of the Galaxy. This has been hinted at, given the thumbs up by George Gomez on Facebook many months ago from memory and someone said that Stern had acquired the license.
Deadpool. Lots of action and humour. A more edgy title, but could see this one selling well.
Suicide Squad. The movie isn't out yet, but theme and artwork alone would make this an interesting pinball machine. Looking forward to seeing this one in the cinema.
Now, my outside pick....I've been wanting to see this as a pinball title since the first movie was released. Wreck It Ralph. Would look great with a new colour display, great look to the movie and the addition of classic video game characters to tap into that nostalgia factor that Stern loves so much. A sequel is also in the works for 2018. Only stumping block here is licensing to include other video game characters.