Clearly this would never happen for reasons we have all been told, but if COG were allowed to make a game around a licence I’d be curious which ones people would opt for seeing.
Personally having seen several super hero games done so far I still would love one set in the Marvel Universe, especially if it was an X-Men game where you happen to be a new member of Charles Xavier’s school, either as a student or a new teacher. Pick your powers, interact with the other X-Men like Kitty Pryde, Jubilee, Colossus and Wolverine, get the chance to date one - my male character and female character would totally be hooking up with Psylocke and Nightcrawler respectively - or even go rogue and side with the Brotherhood or Hellfire Club. Plus battle Sentinels, Purifiers, Apocalypse and Mr Sinister. An expansive game like that in the Marvel Universe would be a dream for me.
Alternatively a game in the Doctor Who Universe where you get to be the Doctor or a new companion would be Fan-Tast-Ic! Travel in the TARDIS, interact with aliens, help out UNIT or Torchwood, face off against Daleks, Cybermen and the Master. All in a season style game with multiple adventures affected by your choices.
Those are my two main picks, I would love to hear yours.