100 chapters? Maybe. East Blue's episodic nature was too stop and start for me, and Hero Aca got through a ton of plot in its first two years. But 200 chapters gets us right to the middle of Alabasta, which is arguably one of the most iconic shonen story arcs of all time. I love hero aca and I think it has the potential to be a long-running Shonen superpower (and it absolutely deserves its strong ranking this year), but nothing it's done yet has impressed me quite the same way Alabasta did the first time through.
I'm waiting to see what getting an anime does for The Promised Neverland next year. It's my favourite thing in Jump besides One Piece atm and it deserves a good performance before it ends.
Even if you want to say Alabasta is the best arc out of all the arcs in both manga we're talking about, which I can't deny but I don't think it's clear, that alone doesn't give it a win when only Arlong is close to the weakest Hero Academia arc. That's not to say I think any of those are too bad, just not as good. Arlong is probably better than 1 or 2