Oh wow, I was the only one who said sequels were the best O_o.
I've always enjoyed a good sequel. Normally, I can understand that they're never quite as well-designed as the original, but I always seem to enjoy them more. A couple of my favourite sequels are listed as follows...
Pirates of the Carribean: Dead Man's Chest. A lot of people, and I mean a lot of people, put a lot of !@#$% on this movie. In my eyes, it was more adventurous than the first, and far more enjoyable.
The Legend of Zelda: Majora's Mask. Sure, it's the sixth game, but also the sequel to OoT. And the sequel to Ocarina of Time could not have been better. Darker, scarier, more meaningful, and completely off-track. It's what the series needed.
Harry Potter and the Chamber of Secrets. My favourite in the Harry Potter series. Where the later books seem to focus on just the works of Voldemort and Harry's efforts to stop him, the second book (and the third) expanded on what the first started; which was opening and exploring this new fantasy world, in a similar way, but also differently. The introduction of the Basilisk, Tom Riddle, Ginny Weasley, Gilderoy Lockhart and the Polyjuice Potion created a really excellent adventure of new discoveries, and a couple of murders along the way.
The Matrix Reloaded. The original was fantastic, but the sequel was an excellent dose of action. The street scene with the billions of Agent Smiths come to mind, and the highway chase was also downright awesome. This film really showed off what Neo and The Matrix world was all about, right before a sloppy "third one."
Paper Mario: The Thousand-Year Door. My respect for Modrill dropped when he placed this game as worst in the series. It is undoubtedly one of the greatest Mario games of all time, with excellent dialogue, a robust battle system, lengthy quest, captivating storyline, challenging boss fights and meaningful themes. By far one of the best games I've ever played.
And yeah.