I don't have a fav movie it depends on the genre.
Today I'm in my mainstream mode so here is my list:

Action: The Matrix, Speed
Thriller: What lies beneath, Sixth Sense
Romantic Comedies: When Harry met Sally, While you were sleeping
Horror: Nightmare on Elmstreet I
Comedy: Spinal Tap, There's something about Mary
Drama: Dead Man Walking, Leaving Las Vegas
Doesn't fit one genre: Almost Famous

Those are the ones that came to my mind first so I guess they are my favourites. hm.

Favourite actor (and best actor ever): Kevin Spacey
Favourite actress: Don't think I have one but every woman should look like Sandra Bullock in While you were sleeping or Speed or Demolition Man then I could get a copy too.