 If you liked One Piece |  ...then you might like JoJo no Kimyou na Bouken Part 7: Steel Ball Run |
The main hero goes on a great adventure for a grand prize. Both manga have distinct/strange art styles, lots of quirky characters, insanely creative powers, and plots involving shady government secrets.
While Jojo was made with Araki making up the story along the way, Oda planned out One Piece from the beginning. I think that if you liked one way of writing, you might be intrigued by the other. Also, both are really weird and have wacky character designs.
report Recommended by ThrowawayDude