It depends on personal preferences. Some people like the anime for its animation and voice acting, while others prefer the manga for its original story presentation.
In my opinion, both have their merits. The anime brings the story to life with movement and sound, but the manga allows for more imagination and detail. So, it's hard to say which is better outright.
I think it's a subjective matter. The One Piece anime has its advantages like visual effects and music, but the manga might offer a purer and more direct storytelling experience. It really comes down to what aspects you value more.