Terminator 2 is a sequel to make all others jealous. That movie had it all. And it was a good Arnold movie to boot. I just remember the whole nuclear scene when the city was going o dust in the dream. That scared the shit out of me. It also used CG to make things possible that wouldn' normally be possible otherwise, so it only added to the movie and not take it over.
Evil Dead 2 is hilarious. It's a good sequel, but my heart really belongs to Army of Darkness.
Aliens 2 was the one movie that really made the whole Aliens universe have its character. There was nothing more bad-ass than the queen at the end of the movie. She was a beast. It's also a good indicator of what can be done with a budget and the people who know how to make the most out of it.
I'm torn on Spiderman 2, I think it is as good as the first one. It's part of a series so I look at it like I look at Lord of the Rings.