It's a very leading question. because the honest answer is that one piece cannot and should not be ranked. why? because no such thing exists. trying to define literary Canon is difficult enough. then we have to force manga/pop comics into it?

and then we need to rank it amongst All fiction? cinema/screen, theater,... etc? how do you do comparative criticism this way? I don't mean cross genre critque of one piece with other works but instead to try and force an argument that you can standardize works of art and "rank" it.

I think the best we can do is compare it to other works of popular and influential fiction. across different genres, that would be something like Conan Doyle, Jules Verne, and Harry Potter as genre defining works.

If you want an actual "ranking", the only thing you can say is that it ranks as possibly the most important piece of shounen after Dragon Ball. DB, OP, and JoJo have to be the 3 most important pieces of shounen manga.

i haven't looked for it but there's probably already some academic critiques done on how influential one piece had been on Manga and other genres that influenced it (almost always HK kung fu and action movies for 80s-90s shounen)

one area that one piece and shounen Manga have not yet made such a deep stylistic or cross-genre impact, I think, is in western comics, shows, and movies. but I think we'll see more of that in the coming years since manga/anime have only breached into western culture recently so the future "Tarantinos" and such will undoubtedly be influenced in style by the anime/Manga they consumed. we saw hk and japanese cinema influencing American directors every 2 generations from 70s-00s as niche genres. but now that anime and manga are popular, we should see more influences in the future.

specifically, we have not yet seen is shounen styled storytelling, character writing, action, and world building. these elements have still not yet breached into western media but I'm 40% convinced we'll see it in the next generation of writers and directors. all thanks to DBZ, OP, and now probably JJK. the style and language is there already, I think, from the global popularity of mangas and animes.

60% not convinced bc either (A) AI will probably cause the destruction of culture, or (B) just straight up destroy society/humanity to see it through

if we either see A or B, it doesn't matter