One Piece might be one of the greatest anime series ever created. It’s an Action Packed Adventure series which started airing in the year 1999.
Special thing about One Piece is that it’s World Building is on a completely different level compared to any other animes. The world of One Piece is extremely rich with details. Every single place in the world has it’s own laws, it’s own culture, traditions, people, currencies and even animals. The author( Eichiro Oda) dives quite deep into World Building.
One Piece has incredible Foreshadowing that no series can match. For example, Shank’s use of Conqueror Haki in the starting of the story only gets explained 500 Episodes later.