Nausicaa was definitely his best work. It was also one of his earlier works and that can be hard to recapture.
I love Nausicaa but I would argue technically it has some weaknesses in the narrative and pacing compared to later works.
So in case someone comes to this without previous exposure Nausicaa may not be the best place to start. It _is_ nice.
I'd love to see the original manga story animated. There are so many beautiful scenes and plots missing from the movie...
However, it couldn't just be a sequel of the movie, as it diverged from the manga story line near the end.