Aliens
Back to the Future II
Batman Returns
Empire Strikes Back
X2

Most of these have already been stated, but...

The Empire Strikes Back
Attack of the Clones (say what you want about Hayden, he acts circles around Jake Lloyd)
X2 (enriches and expands on the original)
Friday the 13th Part 2
Scream 2
Hello Mary Lou: Prom Night 2 (much more fun, where's the DVD?)
Halloween 2 (probably because hospitals really creep me out)
Harry Potter & the Chamber of Secrets (although it's my least favorite of the books)
Phantasm 2 (everything that's good about the original, minus most of what's bad)
Evil Dead 2

Rocky 2
Hot Shots 2
Titanic 2
Citizen Kane 2
2001 2
My Dinner With Andre 2
2 Fast 2 Furious 2
Cool as Ice 2
Good Burger 2

Guess I'm going to agree with a lot of people:

Star Trek 2
The Empire Strikes Back
X2
Godfather 2

On par with the original or just too different to be compared:
Aliens
T2
Die Hard 2
Mummy Returns
Indy & the Last Crusade

T2
Aliens

Also: Hot Shots Part Deux

"Psycho II?" I'm assuming you're kidding...

Maybe he's comparing it to the Gus Van Sant "original".

Many Bond films
Star Trek II and most of the Trek films
Empire Strikes Back
Superman II
T2
X2

Aliens
T2
Godfather 2
Grease 2

DVD Professor wrote that Matrix Reloaded was better than the original Matrix. I saw the sequel an hour ago and I certainly disagree. I actually fell asleep during a long winded monologue on causality and woke up only because my daughter poked me in the ribs- apparently my snoring was embarassing to her!

Superman II
Rush Hour 2
T2
X2
Indiana Jones and the Last Crusade
Drunken Master II

What the.....

Afraid not, I enjoyed it much more than the original.

X2
Matrix Reloaded (Just as good as the first)
Austin Powers 2
Die Another Day (best of the Brosnan series)
MI:2
Star Wars AOTC (only considering the new episodes)

The Godfather Part II
The Empire Strikes Back
Bride of Frankenstein
Star Trek II
Dawn of the Dead
Leonard Part 6

No joke, I thought Young Guns 2 was a lot better than the original. It hasn't been mentioned yet, so I thought I'd throw it into the pot.

Empire Strikes Back
LOTR: TTT
Terminator 2
Aliens
Batman Returns
Batman Forever

probably more I'm forgetting.

While some sequals are terrific, the edge usually goes to the first in the series because that originator created the characters and the universe. Without the original the sequal would have no legs to stand on.

That is why the Godfather II, while excellent, is NOT better than The Godfather.

Empire is NOT better than Star Wars

And T2 is NOT better than The Terminator

Actually the Terminator is superior to the sequal in dozens of ways.

Contrary to what I said above, I will agree that there is one sequal whose supremacy is so incredible that it overshadows its original: Bride of Frankenstein

Is Dawn of the Dead really a sequal?

In some cases the original is so awful that the sequal beats it. Young Guns 2 is a perfect example of this.

I can't believe how many people think Empire is better than the Original Star Wars. Empire was fun, but it doesn't touch Star Wars.

However Clones was better the Phantom Menace.

I also thought Predator 2 was better than the first.

I agree with a lot of the movies mentioned previously and add...

"Road Warrior" (Mad Max 2)
"Babe 2"
"Dawn of the Dead"

A lot of people think "Rambo" was better than "First Blood" - I don't.

I can only think of two right now

T2
Austin Powers: The Spy Who Shagged Me

X2

Empire Strikes Back

Gremlins 2

Superman 2

Star Trek 2

Wrong on both counts.