I think Yojimbo is really tight, though Seven Samurai is famous for a reason and is maybe my favorite. It's definitely the one I rewatch. Ran has some really fantastic costuming and use of color, if a bit larger-than-life.

One non-samurai film of his that's really fucking good is Ikiru. Just. Really neat narrative framing (probably came after Rashomon, which is also excellent) and really captures the intentional gridlock and hollowness of civil administration.

And of course there's the wonderful sleeper bromance of Dersu Uzala. A very touching movie about a russian surveyor and an indigenous trapper dudes-rocking in the woods.