Seconding Guardians of the Galaxy and Interstellar.
Some other highlights of 2014: V/H/S Viral, Gone Girl , Birdman, Clouds of Sils Maria, Maps to the Stars, John Wick, Whiplash, What We Do in the Shadows. All excellent movies. I also really liked Wild Card, but wow does Rotten Tomatoes and its 29% audience score not.
My #1 favourite of 2014 and one of my favourite movies overall, though, is Nightcrawler. No question.