25. Transformers: Dark of the Moon
As well as replacing Megan Fox from the first two movies, director Michael Bay also decided to replace any semblance of a storyline or character arc in favor of sexual exploitation and robot cars fighting, which is fine, just don't spend $300 million on it.
24. Paranormal Activity 3
Given how original and surprising the first Paranormal Activity was billed as, it was disappointing to see them going the "creepy little girl" horror movie route so quickly. Still, at least it continued to stay true to the essence of the original, by offering up plenty of confusing backstory with little to no resolution of satisfaction.
23. Final Destination 3
It seems a movie which features the actual line "Fuck you, Ben Franklin", is probably somewhat aware of its actual worth as a piece of cinema art. That said, Final Destination 3 represents a significant decline in quality from the first two, both in terms of the acting and dialogue, and in terms of how cool the dying is.
22. RoboCop 3
RoboCop 3 did almost everything wrong as a follow-up to two intensely violent movies: it wasn't nearly violent enough. With that, it fell at the first, easiest hurdle, and never recovered.
21. Spider-Man 3
A lot's been made of the Spider-Man Franchise's fall from grace in 2007, especially after two strong, if dated efforts before that. Maybe it was bloated with villains, maybe Sam Raimi got mad and sabotaged it from the inside, all we can know for sure is that street dance montage was hilarious and terrible.