Total Recommendations: 15
Both have clever fights with lots of strategy and characters with crazy powers. Each HxH arc has a considerably different theme, just like the differente JoJo parts.
Both adapt classic japanese stories: Uta Koi is an interpretation of love poems and Ayakashi adapts three horror stories.
Both are about grown man that gave up on their dreams and have a 2nd chance. Both have comedy, though Black Heaven is a sci-fi series about rock.
Prison setting, crazy powers, strange characters and awesome heroines.
Both are parodies full of gross and dirty jokes. Also, both have 2 stories per episode and a lot of nonsense that somehow works in the plot's favor.
Both show the life of a group of otaku and how their lack of self confidence gets in their way, but in a comedic fashion.
Both are adventure stories in which the protagonists are girls that are chased because of a hidden power that they have. Both have a medieval world with some rare and mysterious technology as a setting.
Both have dark stories with tragic heroes fighting monsters. Both feature henshin heroes (The Skull Man originated Kamen Rider) and have a tokusatsu feel to them.
Both are based on several classic japanese stories, with each story having different art styles.
Both deal with supernatural powers. Bleach's author, Kubo Tite, considers Saint Seiya to be one of his biggest inspirations for the designs of the different types of weapons that his characters use in the story as well as the battle scenes.
Both have innovative and different art styles and deal with psychologycal themes.
Both deal with the political, ethical and philosophical aspects of the development of robotics and artificial intelligence.
Saint Seiya has a lot of similarities with HnK. The warriors n HnK represent stars and constellations and each saint in SS represents a constelation. The super human fights, the excessive blood, the melodrama...
Although both series are shounen and have a lot of fighting, both have also tons of adventuring through the world, meeting new people and places and both have a lot of comedy.