Obvious next one would be Youjimbo - later re-made as the excellent Fistfull of dollars (Clint Eastwood) and again as last Man Standing (bruce Willis) - also excellent involving 1920s bootleggers.
Kagemusha - another Samurai masterpiece. Utterly enthralling,
Then for something different - Dersu Uzalla - a slow, quiet, and long film about a " daniel boone" type wilderness guide leading some soldiers in Siberia. A truly great film, compelling throuought, but not an action film by any stretch.
Then perhaps Rashomon for something more stagey. Not a Samurai film though there are samurai types in it.
Arguably kurosawa has a higher "masterpiece" ratio (never mind mere hits) an any other director. All the above would be on anyone's "best ever movies" list
I've not seen Ran, Sanjuro, Throne of Blood, hidden Fortress, which are also very highly regarded, and may well be masterpieces too
And also look out for Tora, Tora, Tora - a superior, standard war film on a Pearl Harbour - I believe Kurasawa did the Japanese-perspective scenes, which have a different, and more powerfull feel from the American main narrative.