If we were doing top 10, Star Wars-- A New Hope would have been 6 or 7, so it just missed my list.
In fact, since we’re tallying:
Runners-up:
L.A. Confidential
The Third Man
Witness For the Prosecution
One, Two, Three
To Have and Have Not
Hey…one from the last 20 years!
I’m not only old, but I spend a lot of time watching movies made before I was born, so I have dozens of favorites made over the last 80 years. But some, although I really like them, I don’t watch much, while others I’ll watch every time I stumble across them on TV. Here are the first five that came to mind:
A Man For All Seasons
The Bravados
Hombre
Quigley Down Under
The Good, The Bad and The Ugly
I really like westerns. Don’t know how Sir Thomas slipped in there.
Casablanca
In the Heat of the Night
The Shawshank Redemption
The Blues Brothers
Dr. Zhivago
Sweet Smell of Success
The Thin Blue Line
My Favorite Year
The Stunt Man
Three Colors: Blue
The Lion In Winter
The Lord of the Rings (as all one film)
Local Hero
A Hard Day’s Night
A Night at the Opera
And extra props to LOTR for the best film score ever written.
It drives me absolutely nuts when people “can’t limit myself” to the designated maximum number of whatevers in threads like this. However, for what I think is the first time, I find myself in that irritating position. My flimsy rationale is that I keep a longstanding list of my favorite films, 72 of them at last count; I also like to highlight my top ten favorite favorites, and after trying unsuccessfully to trim them by half, I now irritate the hell out of myself by exceeding the size limit.
In no order:
Don’t worry. We’ll just count the first five you listed. 
Casablanca
Godfather I & II
Shawshank Redemption
Princess Bride
It’s a Wonderful Life
(sputtering) …but…but…but…
I was going to list the usual suspects as stated above, Planet of the Apes, LotR, The Matrix…here are a few more I could definitely watch over and over :
Cabaret
The 300
What’s Eating Gilbert Grape?
War of the Worlds (Tom Cruise version, but only the first half, really)
Dinner At Eight (the oldie with Jean Harlow)
Hey, those are the rules, man!
-The Lion in Winter
-The Americanization of Emily
-Some Like It Hot
-A Midwinter’s Tale
-The Misfits
The whole movie is magic, but that last scene, the lights in the darkness, makes it immortal.
Okay, I’m glad that this list is for favorite films, not necessarily what I, or anyone else, might consider the best five films. For me that could be a different list.
I think all of my selections but one have been mentioned already, but here goes.
Field of Dreams
A Man For All Seasons
Quigley Down Under
Victor/Victoria
The African Queen*
*This is the one I think is unique so far, but I could be wrong. How can you not like a movie that has the line “I now pronounce you man and wife. Proceed with the execution!”
You do mean the 1933 version, don’t you?
In alphabetical order,
Casablanca (1942)
Crash (2004)
Fargo (1996)
LOTR: The Two Towers (2002)
The Godfather (1972)
Other Dopers dislike Crash, finding it too “preachy.” I don’t like preachy movies either, but Crash is just a good, enjoyable film. I am glad to see a vote for Snatch (2000), which would make my Top 15.
Of course.
You missed Hombre. Two mentions before this list, one after.
That’s one I haven’t seen, BTW. I’ll have to check it out.
For those who named The Big Lebowski, some sad news: David Huddleston, who played the title role in 'The Big Lebowski,' dies at 85
I have a lot of favorite movies. But for this purpose, I’ll list five that I can’t pass up if I come across them channel surfing (even though I have them recorded).
Sweet November (original)
The Goodbye Girl (original)
Butch Cassidy and the Sundance Kid
Harold and Maude
Bringing Up Baby