With so many multiverse movies these days, Letterboxd users have ranked the best of the bunch from many different franchises.
The multiverse is a concept that isn't new to cinema but it's one that has begun to enter the mainstream thanks to the likes of Spider-Man: No Way Home and the upcoming Doctor Strange in the Multiverse of Madness. This new avenue for mainstream audiences will probably create more genre films that rely heavily on the multiverse as a concept.
One thing that makes the multiverse concept fun, is that there could be multiple different versions of the same characters played by the same actors. Unlike a movie with multiple timelines, the multiverse concept allows filmmakers to explore alternate takes on characters and stories.