Shogun's Samurai
One of the best samurai movies ever made, good plot and story and the action is spread throughout the movie. That's good for a being a historical drama.

Swords of Vengeance
A historical drama also, so there isn't so much action, but some good fights, especially the finale. Like in "Shogun's Samurai", a good plot and storyline as it's the same director, Kinji Fukusaku.

Shogun's Shadow
Maybe as good as "Shogun's Samurai", maybe better, hard to tell. But it has much longer action.

Shogun's Ninja
A Hiroyuki Sanada vehicle with very good action throughout the movie and a well-written storyline. Maybe not as good as the others, but it comes up very near in quality.