Mine is The Fall.
Excellent everything. Really a beautiful movie.
Runner ups
2. Baraka
3. Tideland
4. Donnie Darko
5. Big Fish

Oh, hard question.

Primer
Fight Club
Lives of Others
Eternal Sunshine of the Spotless Mind

blergh, I have no idea if that's actually a representative list -- anyway, ordered by length of title not a ranking of how well I like them relative to each other =p

Not in this order, my favorites are:
1. Star Trek IV: The Voyage Home
2. Star Trek II: The Wrath of Khan
3. The Godfather, Part I
4. Lord of the Rings (the Peter Jackson ones)
5. 2001: A Space Odyssey

Um...I'll just list movies that I think are really, really good. 'cause I know that I can't even write a top 5 list, let alone order them.

District 9
Taken
Donnie Darko
300
The Dark Knight
Sweeny Todd
Serenity
Wall-E (Except the ending, didn't like that.)
V For Vendetta

The Gamers: Dorkness Rising
The Gamers
The League of Extraordinary Gentlemen
A Walk to Remember
The Princess Bride

My number one is definitely Oldboy. It's just so perfectly done. Ultimate Reality (by Jimmy Joe Roche and Dan Deacon) is right up there, also. I probably watch both of those about once a month.
I just rewatched Aronofsky's Requiem for a Dream the other night. That man knows how to work a camera. And a lot of Hitchcock's films were just incredible. Rear Window was way too effective for its own good.
The visual effects and cinematography of The Fall were amazing. Anybody that thought Avatar had good special effects has never witnessed Tarsem Singh's Dali-esque hand at a camera. This is one of those films where it seems like nobody has heard of it, but it's something you need to watch, and experience, at least once in your life.Primer should be the official movie of NP, as it's probably the nerdiest thing ever captured on film. Fight Club is probably the one case where I thought the movie was actually better than the book (not that I don't love Palahniuk). And Eternal Sunshine is just incredible. If you've never seen it, check out Palm's collection of Gondry's short form work. He's the type of guy that takes what you know about film and reconstructs it from finger paints and hypnagogia.

In the same vein, I enjoyed Koyaanisqatsi. (But I don't pick favorites.)

I really couldn't get into any of those. I was sad too as I like Philip Glass more often than not -- the whole "tone poem" thing was just lost on me.

I've never been able to pick a favorite movie. It's always changing.

Right now I suppose it would have to be Aurore, because I watched it a few nights ago and it really evoked a lot of emotions.

Mine has to be 2001: A Space Odyssey.

Why?

Because it's awesome.

2001 is good, until the end of the movie. As soon as the drug trip starts, it's ruined.

No, I like the ending, even though I barely understood the ending

'twas a good movie. The books are vastly superior however. Especially since the end actually makes sense in the books.

Edit: 4. Zombieland

Probably the best lighting of any movie ever. It also takes a (recently) cliche idea and gives it a new spin: A plot.

I have many favorites,Some of them are
1.Shawshank Redemption
2.The fight club
3.Rang de basanti

Almost everything by Hayao Miyasaki.

And Pixar.

Other than that:

• A Beautiful Mind
• The Curious Case of Benjamin Button
• The Princess Bride
• Lots of other stuff, but the above come to mind first.

LOTR is the best, also very much liked the first Sherlock Holmes movie (2009). This his a full and updated list ^^.

A list of many movies that have changed my life in ways I generally approve of:

The Princess Bride
Robin Hood: Men In Tights (for that matter most, if not all, Mel Brooks movies.)
Any Monty Python movie
Rocky Horror Picture Show
The Breakfast Club
Mirrormask
Labyrinth
A Walk To Remember
Imaginaria
Dead Poets Society

Probably going to watch this movie tonight, your description sounds good :P

Sometimes it's a bit hard to audibly decipher the speech

I have no well-reasoned ranking for these, but here's a list of some favorites:

Aeon Flux
Alien
Blade Runner (director's cut)
Spaceballs
Strange Days

Seen Primer, didn't get much of it as expected. But going to watch it again (so don't spoil it for me just yet, please!), I know which conversations I have to pay attention to now. Like Cosman said, the speech is often hard to hear if you don't really pay attention.

As others have said, my top pick varies by mood. Here are a few I like which haven't been mentioned so far...

The Cube
Tampopo
Yojimbo
Subway
Diva
That Sinking Feeling
Excalibur
Repo Man
Akira
Cars
Dumbo
The Blues Brothers
Once Upon a Time in the West
Casablanca
Where the Green Ants Dream