I almost didn't watch Nausicaä of the Valley of the Wind because I glanced at its movie poster and skimmed through its plot on Wikipedia and thought, Air gliders and fighter planes? Not my type of thing. I prefer supernatural flight, like the ability I have most nights in my dreams. So I put Nausicaä last in my list of Hayao Miyazaki's full-length films.
After I was done with Kiki's Delivery Service and My Neighbor Totoro, I finally watched Nausicaä and I must say it moved me the most of all the Miyazaki/Studio Ghibli films I've seen so far. It's about a precocious girl in post-apocalyptic times who unknowingly fulfills the prophecy that heals their land of the decay that had overtaken it—nature's way of fighting against the abusive humans.
Totoro is about a cute and furry supernatural being the two children protagonists encounter in the forest outside their new home. Kiki's Delivery Service is about, well, Kiki's delivery service...and finding inspiration to do the things one needs to do. They are all masterpieces, but Nausicaä doesn't send you to your childhood. It has real depth to its story: the protagonist (and giant fungi and arthropods) against the presumably environmentally irresponsible world. It's the animated adventure film equivalent of Al Gore's An Inconvenient Truth (which I still haven't seen yet) sans the statistics, pie charts, and other numerical data.
Nausicaä currently holds a 100% Fresh rating on Rotten Tomatoes.
Oh, and there are black chocobos in the film too.