There are so many, so I'll list some that are my "go to" movies - the ones that I want to watch because I think they're great films or the ones I want to watch I just plain enjoy them. These are all movies I own and have watched (and will continue to watch) repeatedly, forever:
The Lord of the Rings trilogy (though The Two Towers in the one I watch the most)
Tropic Thunder
This Is the End (I watch this at least twice a month. LOL)
Zoolander
Raiders of the Lost Ark and Indiana Jones and the Last Crusade (sorry, Tarshi and TDK, but I cannot stand Indiana Jones and the Temple of Doom)
The Mummy (1999)
Singin' in the Rain
Chicago
Mamma Mia!
Les Miserables
The Great Gatsby (2013)
Django Unchained
The Avengers
Eat Pray Love
The Ugly Truth
Olympus Has Fallen
300
Abraham Lincoln: Vampire Hunter
Harry Potter movies
Okay, I think that's a good enough list with a good enough representation.