I have seen every single film made by Ghibli studio and Nausicaa too. It's not technically a Ghibli film as Miyazaki made it before Ghibli was formed but hey, Miyazaki and Takahata are what makes the studio so yeah!
Nausicaa is actually one of my most favorite ghibli films. Maybe in Top 5 as well, others being Grave of the fireflies, Spirited Away, My Neighbor Totoro and Whispers of the heart. If I choose another, I'd pick Only Yesterday as well.