I’ll piggyback off of this and agree with Zatoichi (the first is definitely worth it) and most definitely the excellent Sword of Doom and Harakiri.

I’m also gonna add a few more:

The Samurai Trilogy - Mifune really gets to stretch his legs and show off some incredible character growth. Great story and action that might not reach Miyazaki’s best but gets darn close.

Samurai Rebellion - a slower paced film (for a samurai movie) that ratchets up the tension with almost each passing scene until it culminates in an emotional confrontation in the fields.

Kubo and the Two Strings - newer stop motion film that maybe stretches the genre a bit but I still highly recommend it. Absolutely stunning.

I have several more that are on high my watchlist:

Kwaidan, Kagemusha, Onibaba, Three Outlaw Samurai