|From the ones I've seen (like six, including Ponyo and the most recent Arriety:
1. Howl's Moving Castle - This one is my all time favorite. I've seen it a lot of times and could see it again any day. It made me laugh and taught me a lesson at the same time.
2. Spirited Away - I like the complexity of the message it is trying to portray in this strange and random sense that is the Miyazaki's style.
Spoiler (mouse over to view)
I specially liked how she matures throughout the movie to eventually help teach some of the characters (like the Baby, NoFace, Haku, etc) and save her parents and herself in the process.
3. Kiki's Delivery Service- First, Ghibli's Film I ever watched. It was very touching and simple compared to other of his movies.
I also watched Princess Mononoke. I taught it was kind of wierd at the beginning, but I enjoyed it very much, too.
"I am a colorful fantasy born on dark nights; a delusion of black and bottomless minds; a thought that dies in the morning reborn by moonlight. What am I?"
- A Night of a Thousand Dreams