So hard to choose only 10, so I'll go overboard a bit:

Shawshank Redemption
V For Vendetta
Gattaca
Le Fabuleux Destin d'Amélie Poulin
Kill Bill (the whole thing)
Pulp Fiction
Jurassic Park
Lord of the Rings trilogy
The Empire Strikes Back
Memento
The Matrix
The Green Mile
Eternal Sunshine of the Spotless Mind
The Truman Show
Mad Max: Fury Road
Groundhog Day
Pirates of the Caribbean: The Curse of the Black Pearl
The Fifth Element

Watch it!  It is very dark.  Just don't watch the sequel, ever.  

This is way harder than ranking games but her goes;

1: Star Wars
2: Lord of the Rings Trilogy (I agree this should be viewed as one film)
3: Alien
4: Dumb & Dumber
5: Der Untergang
6: The Empire Strikes Back
7: Wall-E
8: Pulp Fiction
9: Ace Ventura Pet Detective
10: The Fifth Element

1. The Lord of the Rings Trilogy
2. Forrest Gump
3. Shawshank Redemption
4. Goodfellas
5. Casino Royale
6. American History X
7. Django Unchained
8. Dumb & Dumber
9. Wall-E
10. Tropic Thunder

This list is pretty much impossible to make, any other day and it could look completely different. Only thing that will stay the same is my number 1. I agree with most here that you can't list LOTR individually as I see the trilogy as one complete film, but if I had too then they would fill up the top 3 places. Forrest Gump and Shawshank are pretty much always gonna be 2nd and 3rd for me as well but after that there's just too many amazing films to pick from.

Basically anything like gladiator

This was tough but these was the first 10 that came to my mind when I thought about it

Star Wars: Episode V - The Empire Strikes Back
The Usual Suspects
Monty Python and the Quest for the Holy Grail
Alien
Total Recall
Office Space
Mad Max 2: The Road Warrior
Clerks
The Fifth Element
something about mary

I have far more than 10 movies that I really love, and they are hard to put in order on top of that.  Here is my best shot.

1. The Princess Bride
2. Monty Python and the Holy Grail
3. Star Wars (A New Hope)
4. Sound of Music
5. It's a Wonderful Life
6. LoTR: Return of the King (if I have to pick one)
7. Better Off Dead
8. Forest Gump
9. V For Vendetta
10. Captain America: Civil War


Honorable Mentions (which on a different day could easily make it into my top 10)
Seven Samauri
Raiders of the Lost Ark
E.T.
Grease
Scott Pilgrim Vs. The World
The Karate Kid (Pat Morita one)
Beverly Hills Cop
Willy Wonka and the Chocolate Factory (Gene Wilder one)
Pee Wee's Big Adventure
Jurassic Park
Spider-Man
Batman Begins
Goundhog Day
Rumble in the Bronx
X-Men: Days of Future Past
The Road Warrior
Back to the Future


These are all movies I have already seen more than once, and yet I could pop one in right now and still enjoy the hell out of it.

This topic requires a lot of thought. I know its a few days old, and will probably fall off the homepage. But, if I remember to come back here after thinking about this for a day or so, I'll put my top 10 up.

In no particular order

Collateral
The Dark Knight
The Shawshank Redemption
One Flew Over the Cuckoo's Nest
Airplane
Chinatown
GoodFellas
The Italian Job (1969)
Terminator 2: Judgement Day
Die Hard

Good thing I found this. I was planning on making a similar thread.

10.Night Nurse
9.The Incredibles
8.Spider-Man
7.Casino Royale
6.First Blood
5.A Nightmare on Elm Street
4.The Terminator
3.The Matrix
2.Toy Story
1.The Raid: Redemption

I just watched Double Indemnity and liked it a lot and would watch it again. But my rule is that at least a week had to be gone to put it into my top 10.