I think Mononoke was easily the weakest of Miyazaki's movies but it's the one everyone raves about because it was the first one to see a widespread and non-butchered release in the West on DVD.

The earlier Totoro, Kiki, and to a lesser extent Laputa are all better movies, in my opinion. The former two shine exceptionally by being charming slice-of-life vignettes from a time before that sort of thing was the mega genre it is today, managing to be captivating stories that somehow don't need or contain any kind of villain, quest, or cliché call to adventure whatsoever.

Laputa does -- in spades -- but it's still great. It's got so many villains that it's got two sets of bad guys, but one set of bad guys turn out not to be bad guys and basically the entire damn movie is a flying scene of some type or another and it's fantastic. Castle of Cagliostro is also awesome, and it was arguably one of those pivotal Citzen Kane style moments for the medium that turned out to be surprisingly influential to subsequent works, both animated and not. (And also introduced an entire generation to the only version of Lupin who is not an huge asshole, much to the surprise of everyone who watched this movie first and went on to check out... any... other Lupin III works.) Cagliostro was so influential that Japan's (former) Princess Sayako based her real life wedding dress off of Clarise's dress from the movie, and said so.