As this thread has taken off a bit I feel obliged to give it a better response than my initial smilie based one

It is a very strange list and I'd replace at least ten of them even if I could only use films watched in the last two weeks but I'll go with these as films that would probably be in my favourite 100:
Blade Runner
Eternal Sunshine of a Spotless Mind
Memento
The Terminator
A New Hope
The Empire Strikes Back
These as possibles:
Alien/s
Donnie Darko
The Sixth Sense
The Shawshank Redemption
Terminator 2: Judgement Day
Being John Malkovich
Return of the Jedi
These as ones I thought were above average or good but wouldn't make my list:
Unbreakable
Bill and Ted's Excellent Adventure
The Goonies
The Green Mile
Gladiator
Scream
The Ring
Ben Hur
American Beauty
Labyrinth
The Matrix
Empire of the Sun
Jurassic Park
A Beautiful Mind
Top Gun
Spartacus
Back to the Future
Ocean's Eleven
Fight Club
The Dark Knight
Man on the Moon
Minority Report
Twelve Monkeys
Forrest Gump
Monty Python and the Quest for the Holy Grail
Raiders of the Lost Ark
Men in Black
The rest I either haven't seen or I thought were a bit rubbish. Razorback has already highlighted the most dubious

Special mention for the new Star Wars films that I thought were really poor and a massive disappointment. I was also a huge fan as a kid. I had all the toys and was in the local paper with my collection

, they'd be pretty valuable if my dad hadn't thrown away all the boxes when we moved house

I've still got one of the original cinema posters somewhere from when they showed the first two back to back "together and as they should be seen on a big screen" might also be worth something if it wasn't covered in sellotape
Anyway, they were just a waste of time. Not totally awful but just really really dull. I don't even think of them as being part of the same thing and still think of Star Wars as a trilogy. It seems hard to imagine anyone who loved the three proper films first time round feeling anything other than disappointed and even a little bit betrayed by the new ones. As though a little part of their childhood has been tainted. I went a bit melodramatic at the end there. Sorry about that.
Also Prince of Thieves for being odd. It could have been a really good family film if it wasn't for a couple of 'unsuitable for kids' type scenes and the really weird comedy rape scene at the end. One of the more inappropriate scenes I've ever seen and really quite bizarre.
And lastly Dune just for being awful. It would be on my worst 100 list. A total mess of a film, like it's been edited together in the dark and nobody bothered to check the end result.