I've been meaning to watch more movies, but I tend to spend my free time with video games, which are a massive time sink. These are the ones that stand out to me so far. Most of these are extremely well known, so I'm only going to comment on a few of the standouts or the more obscure stuff.
Grave of the Fireflies- This is a gut punch of a movie that leaves a long lasting impression. I've only seen it once, but I remember it clearly.
Akira
Blade Runner -both these movies kill it with their atmosphere, and can be thought about and interpreted in many ways. I respect both immensely.
A reliable good time - I never get tired of seeing any of these movies, they're the ones I come back to repeatedly.
Batman: Mask of the Phantasm
Batman: The Dark Knight
Captain America: the Winter Soldier
Die Hard
Casino Royale
Inside Out
Galaxy Quest
Kung Fu Panda
The Lord of the Rings Trilogy
Megamind
Pirates of the Caribbean
The Princess Bride
Spiderman 2
Star Trek 6: The Undiscovered Country
Terminator 2: Judgement Day
Transformers the Movie(1986) - One of the mainstays in my childhood, and at least one reason I'm still such a Transformers fan. It's strongly style over substance, almost a hair metal music video, but that's not a bad thing. It's got constant forward momentum, great music, awesome art direction, and very good animation.
3D Movies - I'm a huge fan of 3D movies and these are the ones that I feel truly used the format to it's full potential.
Lichtmond 2: Universe of Light - This is a movie very similar to Disney's Fantasia, animation that is meant to be an interesting visual to go along with the music rather than trying to tell a story.
The Young and Prodigious T.S. Spivet - Set in a slightly surreal world, it's a story of a boy's journey across the country, and dealing with a traumatic event in his recent past. It's a subtle and quiet movie for the most part, and quite touching.
The Taking of Tiger Mountain - a Chinese action movie with a pretty good plot, although the ending is a little weird. Excellent action and cinematography throughout.
Hugo - A film about an orphan finding his place in the world and solving a mystery about an old man he meets. It's a great story, well shot, and has spectacular 3D.
Comedies
The Emperor's New Groove
Harold and Kumar go to Whitecastle
Spaceballs
Hot Fuzz
Airplane!
A Funny Thing Happened on the way to the Forum - This one has a sense of humor a lot like Airplane! and I highly recommend it to those that like that movie.