My list of sequels that destroyed their originals:
Star Wars Episode V: The Empire Strikes Back Because George Lucas didn't have much input in the making of this film it meant this film was made by people who actually know their craft.
Mad Max: Beyond Thunderdome I know some say Mad Max 2 is better but to be honest I don't remember Mad Max 2. I do, however, remember Beyond Thunderdome. There were many memorable characters and plenty of quotable lines. And then there's that Tina Turner song!
Toy Story 2 Pixar builds upon the first and makes the second even better. The introduction of Jessie as an abandoned toy added a level of sadness I hadn't felt for toys before. I actually went home and played with my toys after seeing this film.
X2: X-Men United Better performances and a better story. The performance by Brian Cox as Styrker is perfect; I understood his pain and what drove him. For the first time we get to see Wolverine really unleash his fury on those soldiers with his claws!
Aliens Do I even need to say why this is better? But it is safe to say this movie has a certain dollar value attached to it.
Star Trek: The Wrath of Khan KKKKHHHHHHAAAAAAAANNNNNN
Superman II Much better than the first! Krypton criminals General Zod, Ursa and Non are sentenced by Jor-El for banishment into the Phantom Zone. They somehow manage to escape their confinement and immediately cause havoc on earth. Of course General Zod continues his Kyptonian rebellion by demanding obedience and servitude from humans. Meanwhile Clark Kent loses his powers and gets to experience what life is like as a normal human. The high point is the climactic battle between Superman and the Krypton badasses!
The Lord Of The Rings: The Two Towers While not as deep as the book the film does delved more into the lore of LOTR. The pacing was much better too. Fellowship suffered from too many slow moments. The Helms Deep battle was the first of its kind too. I don't think I've ever seen that many CG orcs on screen!
Spider-Man 2 Peter Parker continues his struggle to maintain a relationship with Mary Jane, juggling his studies, holding down a job, and fighting crime as Spiderman. You insert Doctor Octavius (who isn't exactly a bad guy but a misguided soul consumed by his passions) and Peter's best friend Harry (who is descending into madness and the role his evil father held) and all these plots are organically weaved together to make the pacing a much better viewing experience than the first.
Terminator 2 Nuff said.
The Dark Knight This film stands apart from all other superhero films. It's not a superhero film but something more. This is a crime drama. And then there's Heath Ledger.
The Karate Kid Part II I liked this film more than the first. The relationship between Daniel and Yukie felt wooden but thankfully their screen time together was very limited. I liked that this film goes deeper into the main characters. I also like that it literally picks up where the first left off. We can see John Kreese's reaction to losing his trophy and how Mr. Miyagi handles it. We travel to Okinawa and see Mr. Miyagi's family and land. We even learn that fighting in Okinawa is "for real." The fight scene at the end is much more intense than the first film.