In my opinion, it is One Piece. One Piece was an Anime created in 1999 and currently has 1058 episodes.
Many people dislike one piece for it being to long or to bland, but I disagree. I think every single episode is detailed and interesting. The creator of the Anime is amazing at forshadowing future events. That is one of the reasons it is detailed, because there is always some kind of special event or scene in the episodes, that you have to really concentrate to notice.
There are also mysteries in the Anime encouraging many people to come up with theories and answers to many questions that have not been answered in the show.
There are some characters in One Piece that make the show amazing. There are also many moments in the show that are very emotional and serious, but at the same time it is filled with funny humor and goofy moments.
Something that probably goes on the more interesting side of the show are Devil Fruits.
The story is mainly about a man who looks for a pirate crew to help him find the One Piece, a legendary treasure that gives you the title "Pirate King." In the story the former Pirate King, Gol D. Roger, before he died, told the world that his treasure was hidden somewhere in the Grand Line, one of the most treacherous seas ever, and every pirate has gone looking for it. therefore starting the Great Pirate Era.
Some of my favorite character are:
In conclusion, I recommend that if you have free time, you should try watching this Anime.