Pretty much agree with the above in regards to a favorite. I definitely can mention a few, maybe from different genres and decades -- and not only that, some directors with numerous movies that I enjoy.
Movies:
Conan the Barbarian (1982)
Probably closest to a favorite as I can get. Growing up on the farm I had no shame, I ran around in my underwear during the summer and slayed many a frost giant wielding long curvy branches and fractured cow skulls. To this day, this movie soundtrack probably remains my top listened ever. I never tire of it. That's part of what also makes a movie great...an epic soundtrack.
Starship Troopers
I remember being so excited buying this on VHS during it's release and being absolutely blown away by the awesomeness I probably watched that VHS until it turned to dust. I quoted this movie for years and at times still find myself quoting it. Another soundtrack I have abused. Also has the worst sequels EVER.
Tuvalu
Some of the most memorable movie moments I will ever witness. I won't spoil any but it's a beautiful piece of artwork. I first watched this in my mid-teens when I ventured outside of American film and music. I watched many foreign movies and this was one of the few worth remembering.
Låt den rätte komma in
There use to be a website back in the day that had high quality streams of European new releases. Some movies still in theaters. It was a really good low-key site. It got shut down but at that time I discovered this one and fell in love. I'd honestly say this is my favorite 'vampire' movie. Us Americans know it by the name Let the Right One In. Like many great movies across sea, they get terrible US remakes.
Tucker & Dale vs. Evil
I am a huge fan of horror-comedy. This movie was so perfect and to top it off...Alan freakin' Tudyk. Enough said.
La cité des enfants perdus
City of Lost Children. Ron Perlman before he was known. Beautiful movie. I can't even describe how surreal and gloomy it can be. Pretty much love Ron in all Del Toro films too.
Blended
It's hard to narrow down favorite comedies. So many different sub types and most of them are pretty enjoyable. This one I can easily pick. Now I'm not a big Adam Sandler guy and I've seen the previous movies he did with Drew and was meh about them. This one however, is laughs from start to finish. Great acting all around and brings so many characters and silliness.
I could name 100 others but I won't bore anyone.
Directors
Wes Anderson - This is one of the few directors that when recommending to others...warn that he is almost entirely an acquired taste. When I first saw a film of his I didn't like it. When I watched another I kinda liked it, then I watched more...and you get the picture. My favorite by him...hard to say. Rushmore and Fantastic Mr. Fox definitely. The Life Aquatic with Steve Zissou too.
Anders Thomas Jensen - found during my mid-teen exploration of foreign cinema. Greatly enjoyed his first three movies, but have not seen his new one. He brought Mads Mikkelsen to fame.
Ingmar Bergman - I admit I've only seen maybe four of his movies, but the ones I did see I enjoyed. Wild Strawberries and The Virgin Spring easily being the best.
List goes on. I'm too tired to write up more.