Naoki Urasawa: "The only thing all humanity equals in, is death", "my hatred is far greater", "the monster inside me is getting bigger". But imo he lacks the extra factor that pushes him higher among the best mangakas.
Eiichiro Oda: "the golden bell is in the sky!" "You are my nakama!" "Say you wanna live!" "Thank you for taking good care of me until now...i was...happy". But imo the post timeskip arcs have way too clunky of a storytelling, unimportant focal points and dragged pacing.
Takehiko Inoue: ...countless legendary moments from Vagabond. Weakness...none too noticeable really.
Kentarou Miura: The entire Eclipse arc was a masterpiece. But the entire story lacks resolve. Griffith keeps getting cooler and kingly without doing much, Guts keeps getting sadder and more gloomy, the story eventually became lighter and more comedic as the author lost the direction and getting in circles, no resolve in sight.
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The final battle is imo between Oda and Inoue. Oda is an extremely tough contender with uis consistency and relentless creativity. But for me, the victory belongs to Inoue. His canvas create a poetry, his storytelling moments are impeccably original, he even made the culmination and ending of Vagabond in a separate volume, despite the original manga series itself going on a hiatus. Inoue-Sensei, you are truly a master.