Cover Art: Criterion vs. Eureka
I am going to now play the part of the artsy-fartsy picky guy here, but I must say that I prefer Eureka's cover for the film over the illustrated cover from Criterion (see both samples in the links below below).
Onibaba, Criterion: http://www.criterion.com/films/665
Onibaba, Eureka: http://eurekavideo.co.uk/moc/catalogue/onibaba/
I love how Eureka uses the original typography from the movie posters... combine that with the duotone flood of the ominous susuki grass, and the gorgeous-yet-unsettling glare from Jitsuko Yoshimura, and IMO you have yourself a fine representation of the film's mood.