Ok, I'll bite. At the level of world building and themes One Piece talks about political power vs corruption, freedom vs order, one world government vs nation-states, racial issues, immigration. And it does so in a very competent and morally grey way.
Berserk died after golden age.
The only plot progression from Chapter 126 - Chapter 307 was just "Griffith comes back and gets everything he ever wanted".
Isidro is a joke character with no depth who is not funny or interesting.
Schierke, a loli witch who has a crush on Guts, turning Guts' crew into a harem.
This new girl Isma is about as interesting as a cardboard cutout.
Not to mention that unfunny comedic pirate that never stays dead. It's shit. You're literally seething because OPchad pointed out how superior was Marineford to changing the whole dynamic of the series compared with Shonenzerk's shitty story.