Spirited away, just because I saw it as a child and it got me hooked on Miyasaki for life. It remains one of the most fun ones for me. It has the right balance between reality and fantasy, between fun and action/danger.

It also has that feeling of looking at a strange world as an outsider that I love, which is the reason I liked the first harry potter film/book for example. The wonder of a new, strange world with new rules that we do not comprehend.