Least favorite Ghibli?
My general impression is that while they have made some absolutely wonderful movies, they have a few stinkers, too. The only one I haven't seen (including Ocean Waves and this one) is the Cat Returns, so I can't comment on it. My least favorites are Nausicaa, Laputa, and Only Yesterday.
Favorites are Porco Rosso, Pom Poko, Yamadas, Spirited Away and Castle of Cagliostro.