Hokuto no Ken, JoJo no Kimyou na Bouken Part 1: Phantom Blood Recommendations
Classic manga based on immense power and manliness. Great reading.
Both series feature characters with very masculine builds and designs, with Jonathon and Dio having designs heavily inspired by Kenshiro and Shin respectively. Both series are also infamous for having numerous gory scenes on a level not seen in modern Shonen, and are less heavy on providing Shonen tropes than most other series (although that's not to say they're absent from the series).
Hokuto no Ken was one of the main inspirations that made Hirohiko Araki write JoJo, that's why both series share a lot of similarities, both thematically and stylistically. First off, the art styles are quite similar, especially in depicting fights between huge muscular men. The characters are also similar, with Jonathan Joestar being proud, stoic and kind, as well as having a strong sense of justice and an explosive determination, much like Kenshiro. Dio, on the other hand, is physically similar to Shin, although his personality is more similar to Souther, since they both are overly ambitious and want to rule weaker people. The plot
JoJo's early season's were practically an esque of Fist of north star, the author himself once said how he liked the manga and it inspired him, both of these are great works, love them both, totally recommended.
Hokuto no ken has a tone of tragedy and sadness in it too though, this is however more shallow in JoJo