I would love to see an X-Men film that faithfully adapted either Executioner Song, Fatal Attractions, or the Age of Apocalypse story arcs as they are easily the three best written stories in the X-Men series and at least a 100x better than that overrated Dark Phoenix Saga that every single X-Men related medium feels they have to do their own take on...

In terms of an original series, I want to see an animated film based on Johnny the Homicidal Maniac.