Favorite of all time - Lord of the Rings: The Return of the King (saw it 5 times in the theaters)
Favorite I can watch any day, any time - The Fifth Element (watched it over 100 times, no lie)
Recently released favorite - Avatar
Favorite fan boy movies - Star Wars, Matrix, Transformers
Return of the King is a fantasy masterpiece. All the culminating events from Fellowship and Two Towers make Return of the King an epic ending to a great story line. Not as good as reading the books, but seeing it visually was epic.
I had The Fifth Element on UMD for my PSP and I would watch it at work. Also, before I started work after high school, there was a whole month that HBO had it and I would watch it almost everyday. Sometimes twice a day. Its just a fun movie.
Avatar is another fun movie. You get so involved with the characters, theres loads of plot development for a big budget special effects movie. The visuals are stunning and James Horner does another epic score. I had to download the soundtrack after I saw it the first time.
Star Wars because its Star Wars

, Matrix because learning Kung Foo in seconds

, Transformers because its Transformers and it has a 2010 Camaro as a main character