As a major Miyazaki fan, Porco Rosso is the movie that I keep coming back to. Broadly a comedy in the manner of so many classic Italian movies of the 50s (think Don Camillo), it's also a nostalgic love-letter for the magic of flying in the old biplanes that captures a pre WW-I feeling AND an elegy for the loss of innocence that that war entailed.
There's a lot to enjoy every time I revisit it, and not least are the deft "blink and you'll miss it" resolution at the end and the undying faith in humanity that the film itself represents.
For me, Miyazaki might have made better movies, but this is the one that I would fly into the sunset with.