Twilight
For a series of movies that are particularly beloved because of the uncomfortable acting and dialogue, Twilight still manages to be overrated by its fan base. One of the major problems is that the behavior in the film is completely contrary to how real human beings (or vampires, for that matter) should be interacting with one another. Critics widely dislike Twilight, but still, there is a consistent fan base that argues that the movies are actually redeemable.
Harry Potter
As a whole, the Harry Potter movies are charming and worth the watch. The acting is good, the story is true to the books, but the cinematic depictions of the main characters leave a lot to be desired. These movies ended up becoming some of the original "big name + high budget = high profit" templates that we see in modern cinema nowadays. The films themselves, while they are truly charming, are definitely way overrated.