One Piece is definitely the best anime serie on the planet. One piece has been around for over 10 years and still continues to be amazing. One piece is about pirate Luffy who wants to become the king of all pirates. Luffy has eaten a devil fruit which gives him special abilities. Luffy can stretch every part of his body like rubber. In One Piece, Luffy gathers an awesome crew and travels the seas in search for gold and adventure. One Piece has a great story and does not have a lot of filler episodes. One piece filler episodes are generally good. I once thought the G-8 filler arc was canon because it blended in with the main story so well. One of the reasons the filler episodes of one piece are generally good is because the producers first ask the mangaka(Eiichiro Oda) for permission. Some fillers are still terrible though. The goat island fillers for example. You definitely want to skip those.
Added opening songs for all episodes. One Piece definitely has some of the best openings ever!