I can't think of a top 5 - it really comes down to the mood as to whether I want to watch a good film or something to do while I eat popcorn - some of them are good films - some downright cheesy - all have been entertaining:
Platoon
The Shawshank Redemption
Sunshine
Fight Club
Unforgiven
There will be blood
No country for old men
The Incredibles
Ferris Buellers Day Off
Heat
The Crow
Point Break
Gladiator
The Untouchables
Avatar (3D)
Sin City
AI
Groundhog Day
The Assasination of Jesse James...
Rainman
The Colour of Money
Wall-E
Predator
The Bourne Identity (& sequels)
Event Horizon
300
The Green Mile
The Sixth Sense
Dances with Wolves
Book of Eli
The Truman Show
Braveheart
Trainspotting
The Terminator (& sequels)
Pitch Black (& The Cronicles of Riddick)
Superbad
Fast & Furious (& every corney sequel)
And how can we forget "Scumbag millionaire" - inc 5 members from this forum who featured inc 2 FTO's.