Hokuto no Ken, One Punch-Man Recommendations
Although their setting and mood are different (with OPM being a comedy and HnK being more tragic), both manga focus on an overpowered main character, who kills enemies almost effortlessly. Both have great art and over the top action.
Both series are about an extremely overpowered main character and most of the situations in these stories revolve about the MC dealing with much weaker enemies, usually defeating them in one hit. Both series eventually reach a point where they can't one-shot everything anymore, but for the most part Saitama and Kenshiro are never really in danger. The biggest difference between these two is, that Hokuto takes itself dead serious, while OPM actually makes fun of mangas like Hokuto or Dragon Ball and only occasionally gets serious.