Superman v Batman: Dawn of Justice (2016)
Another "versus" film, this one not quite so successful.
I've never really like the shared superhero universe concept. I believe that they are each better as the sole hero in the own story; forcing them together in one world is to the diminishment of both. Here, for example, for much of the film, Superman is reduced to effectively being the villain in a Batman story, yet a villain that we know Batman will not ultimately vanquish, while Wonder Woman is merely a bit player.
On the plus side, I liked the Superman & Lois stuff, especially the way Lois was portrayed almost as a co-equal fourth hero.
The ending is reminiscent of Star Trek II, complete with Amazing Grace on bagpipes. Somehow, I doubt that Superman's death will stick any more than Spock's did, making it hard to feel the requisite sorrow.
The Empire Strikes Back, and its famous unresolved ending, have a lot to answer for.