Princess Mononoke is a beautiful film. It's one of the Ghibli films that's transcended being dismissed by friends and family that don't like animated media, let alone anime. Good choice!

Mine is Porco Rosso. The setting and characters (like all Ghibli movies lol) make me feel so comfortable. It's fun and exciting, with a lot of small, genuine moments. Plus, the airplanes and idea of sky pirates is rad.

There's a game being worked on called The Brew Barons that's pretty much "Porco Rosso: The Game", and I'm friggin stoked for it.