Own: Alien, Aliens, Predator
Alien and Aliens are Sci Fi classics. Both of these movies are excellent and that Sigourney Weaver nude scene, that wasn't even a nude scene, was incredibly hot. The original Predator is awesome with Arnold and Carol Weathers. Even though the Predator's face looks like an open vagina, it's still intimidating and could kick your ass.
Disown: Aliens 3, Alien: Resurrection, Predator 2, Alien vs. Predator, Alien vs. Predator: Requiem
No offense David Fincher, but Aliens 3 was not good. Alien: Resurrection, with Winona Ryder nonetheless, was horrible. Not to mention, those stupid Alien vs. Predator movies. I only own Alien and Aliens and I still need to pick up Predator. These sequels are a complete waste of time so don't bother.
Own: Star Wars: Episodes IV - VI
Everyone knows about the "first" Star Wars franchise and how good it was so I don't even have to explain why they're on the list. I think from now on, everyone should just assume Star Wars is on the list, without even having to write it down.
Disown: Star Wars: Episodes I - III
Hayden Christensen. Two words that brought down the credibility of the Star Wars saga. He was unable to have any chemistry with Natalie Portman and wasn't even threatening as Darth Vader. His stoic/wooden demeanor makes me wish these movies were never made. Respect to Lucas, but c'mon, better casting and just better overall movies would have been appreciated.
Own: The Terminator, Terminator II: Judgment Day
How awesome was Arnold in these first two movies? He was the villain in the first and hero/protector in the second. It was a clever turnaround and I think I liked the second one more because Arnold was a good guy who kicked ass (plus it was a better overall movie).
Disown: Terminator III: Rise of the Machines
This is where the franchise went a little south. First, Arnold has to defeat a female terminator (kind of wack) and say cheesy lines like, "Talk to the hand." It wasn't clever and Arnold lacked humor in this one. I love his one-liners in the second and third was just a let down. Christian Bale in the next installment, Terminator 4: Salvation is gonna be awesome just because he's in it.
Own: The Matrix
The Matrix is a modern classic. Keanu was perfect in the role of Neo and I don't care what anyone says about his acting because he nailed this one. The whole movie was interesting and it made me believe in that world (or that we live in The Matrix). It was cool, fun, exciting, interesting, etc. It had it all.
Disown: The Matrix Reloaded, The Matrix Revolutions
Then of course came the sequels. I have heard people say they like them, but most people would disagree. I really didn't like Neo flying around and I thought Morpheus' character was too understated in these movies. He was so mysterious and cool in the first and then became a background character in the sequels.
Own: Back to the Future
Who doesn't love the first Back to the Future? It's just awesome and somehow Michael J. Fox seemed cool. The movie is fun to watch and Doc (Christopher Lloyd) is hilarious throughout the movie. Crispin Glover is also really good and needs to be in more roles like this one.
Disown: Back to the Future Parts II and III
I mean, I own the entire trilogy but Parts II and III aren't very good. Maybe it is actually one of those cases where the first is so good that the sequels can't compare. Whatever it is, they just don't measure up. The future in the second one was kinda stupid and not really "futuristic" while the third was set in wild west 1885. I didn't like the Doc's love story either.
In regards to Alien: Resurrection, the movie didn't have a set script. It was just story boarded. It wasn't fantastic, but at least Jean-Pierre Jeunet tried to shake things up a bit.
As for Back to the Future II, any film that makes a ten year old think deeply about the space/time continuum is good in my book. Again, they tried to do something new...or as new as a sequel can be.
In short, I can't disown any film where the filmmakers do something atypical.
Oh yeah, I gladly disown anything involved with The Matrix because I can't find anything original in any of the films. Read Simulation and Simulacrum, and you pretty much have the screenplay for all three films.