one piece is one of most unique shouen series in history bcoz of certain elements like :
1.focus on each crew member showing why they are the way they are
apart from main protagonist luffy every other crew mate has a proper back story,character,skill ,fighting style and a propose on the ship
2.natural flow of story : another grt thing about it .Oda sensei's way of story telling unlike other shounen manga like dragonballz and naruto charcter dont just power up arc by arc as the story progress they grow stronger with time
3.even if the show is 700+ episodes you don't get bored coz each island has its unique traits and villains and fun
4.all around one piece make it worth your time