The Samurai Trilogy with Mifune blew chunks. A really bad movie. "Sword of Fury" starring Takashi Hideki as Musashi and Matsuzaka Keiko (hubba hubba!) as Otsu is much better.
The 1962 version of Chushingura is, visually, a very beautiful film. It is a very square-jawed, heroic telling of the tale, and, as befits a film directed by Inagaki Hiroshi (who also did the Samurai Trilogy) it is very beautiful to look at. A lot of cherry blossoms and koto music. Dramatically, it is saved by the superb acting of the actors who play Oishi Kuranosuke and Kira, respectively. They were both classically trained Kabuki actors and it shows. I wouldn't agree that Mifune is wasted; his over-the-top scenery-chewing turn as the ronin spearman Twaraboshi Genba is one of my favorite bits of overacting of all time. But, that's pretty much all he ever did except when he was directed by Kurosawa.
I also recomend the uncut version of "Hidden Fortress" by Kurosawa. It drags in places, but it is a really rousng film (kind of a parody on the conventions of the traditional Japanese period piece), and it has the best spearfight ever put on film.
Agree on "Seppuku" and "Sword of Doom". "Seppuku" is, I think one of the best films ever made (if incredibly depressing), and one of Nakadai's best roles. "Samurai Rebellion" is not anywhere near as good, but it has a LOT more swordfighting in it. I haven't seen it sine I was a teenager, but "Kill!", also directed by Okamoto Kihachi (a very good action director) was very enjoyable, as I recall.
Also, what you think is good depends on what you're looking for. If you just want swordfighting, there are hundreds of old chanbara films to choose from.
Finally, I have to say that neither "Ran" nor "Kagemusha" measure up to Kurosawa's earlier work, IMNSHO. Very pretty to look at, but somehow lacking in that essential Kurosawaness. But, to each his own.
I thought "Heaven and Earth" was a really lousy movie. Great spectacle, but empty.