Only because a manga is running for so long doesn't mean it's the best. One Piece has one of the best world buildings in all of manga, nobody denies that. Yet you already outlined one of the stories biggest problems: It has become repetitive, especially post-skip.
The formula for literally all OP arcs is the same: Sail to a new island, meet the nice guys (most of the times a lady), hear about their problems and the bad guys, flashback about the tragic past, defeat the bad guys, have a banquet, repeat.
Make no mistake, OP is still good and a fun read. I just can't put it anywhere near some of the mentioned mangas (HxH, Jojo, Berserk, Kingdom) when it comes to storywriting.
Yes but when you meet nice guys, island, their issues, bad guys, you need ideas. Yes most of their past are sad so cliché but still you need to give ideas.
OK let's compare to those mangas :
- Jojo : one tome has 4 or 5 chapters when OP has 10, the double. Jojo has 941 chapters i think (at least the last one i read) so just divide by 2, it means 60 tomes for jojo. Plus it's monthly release. And also, it follows lots of new characters and sometimes you have the old characters who are coming. Yes the manga is well drawn, good stories but i can't compare to OP.
First, the worldwide success of One Piece when Jojo is way behind. The pressure Oda has is not comparable to Araki.
Yes the lenght of the manga doesn't mean it's the best, but 24 years at the top, it's like day and night.
How could I compare one who has only one week to draw and need to give his ideas so he can't deepen his story to one who has a full month to think just for one chapter and draw the same amount of page that Oda is doing in one week ? Come on, it's like me who have 1 month for a project and you 1 week to do it and i take all the credits. And that's for 24 years at the top ...
And the main thing about Jojo, it follow new characters from another timelines. So the author has a complete new story with new characters everytime because he can't add anything more to the oldest when he finished their stories. While Oda is still carrying the same characters, he doesn't have that freedom.
If you watched Bakuman, you undestand very well that weekly mangaka needs to give their best if not they are kicked out.
- Berserk same, monthly. Less tomes and chapters and it follows mainly Guts. I love berserk but there is a reason why it's really underrated and not popular because first, not everyone like berserk's story, and second it's dark fantasy and a seinen. When One Piece covers lots of people, it's shonen. When you have more popularity, you need to follow the rules, can't really do what you want. Berserk too was really boring at many moments. But the author or Berserk has time, doesn't have too much pressure, follows only one character who is a calm, mature, serious. He doesn't even need to care about Guts because Guts grew up with his battle and experiences when the Straw Hats still need to grow up.
- HxH, this one is very good but again the manga is more famous because the author takes so many breaks : many!! If not, the manga since 2004 has released 10 or 12 chapters in 1 year when Oda was releasing 50 chapters per year but only due to health issue, he takes 1 week in 1 month. You know why Togashi took so many breaks ? Because he couldn't follow the rythm of weekly release and had a burnout.
That's what i am trying to explain to you. Being at the top for so many years with a rythm of mammooth, how could we compare to others mangas ?
- Kingdom has 58 volumes and a good amount of chapters. Weekly release so we can compare One Piece with this one.
The difference between them are One Piece is 10 years older than Kingdom so we have an extension of weekly release for One Piece for 10 more years. We don't know if the author of Kingdom could do that, maybe or maybe not. He works with less pressure than Oda which was directly put in the first ranks. The manga Kingdom was edited just a few years ago by western editors, why so late ? because it's less popular and interesting than One Piece. Good story yes but why it lacks in sales, popularity or notoriety ? because One Piece is more connected and loved by readers because the manga is better. That's a fact.
Even the pages, the latest chapter of Kingdom has 6 or 7 pages where most of them are empty beside the characters, and the backgrounds are mostly white. When for One Piece, the amount of details in every pages are astonishing.
One Piece is completely different, millions people follow that. We could say popularity doesn't mean = better manga. But the fact One Piece is leading all others manga for this amount of time and sales that the history of manga has never seen, it's revealing how One Piece is above Kingdom.
Conclusion as I said : One Piece is not the best manga but no manga/mangaka is better than One Piece and Oda.
The perfect manga doesn't exist but if we remove the flaws and some boring moment of OP, it could be the best.
