Don Bluth was far superior to Miyazaki. Also, Miyazaki was a poor father and his kids movies sucked (i.e. tales of the earth sea) because he was basically forced into following in his dads footsteps.
https://www.ursulakleguin.com/adaptation-tales-of-earthsea
It really is unfortunate that this went the way it did --- I'd dearly love for Earthsea to have a film version worthy of the fact that it was one of the first books to ask the question, "Can there be fantasy which is not a retelling of _The Lord of the Rings_?" and to answer with originality and a deep insight into what fantasy has to say about human nature.
Kiki's Delivery Service, Totoro, Castle in the Sky, Arrietty, etc. are all watchable at any age.
Even the more mature films like Princess Mononoke would be unlikely to garner more than a PG rating.
I love Secret of NIMH, All Dogs Go To Heaven, etc. but let's not whitewash over history. He also did "A Troll in Central Park".
For every mediocre movie like Earthsea, there's also fantastic movies like Porco Rosso, Spirited Away, Naussica, etc - all of which I watched as a "kid".
They both had their highs and lows. Seems rather pointless to try and bench them against each other.
Porco Rosso literally reuses music, animations, etc from his other films. I enjoyed the film because a fascist pig cassanova was a fascinating premise - but it's very much derivative.
I bench them against one another because my partner is obsessed with Miyazaki and finds Bluth films to be mundane in comparison. Miyazaki has far more cultural capital today than bluth - which is absurd since more Americans grew up watching the land before time than they did watching anything Miyazaki made.
Sure, it’s conceivable for Ghibli to be successful again with a new talented director, but it won’t be Miyazaki’s nor Takahata’s Ghibli anymore.
Edit: The downvote is a lot less helpful than an explanation.