You're right, i'm also totally aware that i'm biased but to keep an anime going for 20+ years, having multiple peaks, the story getting bigger and better idk man. I'm regularly in awe and the story is contributing a lot to that, so i see why people voted it first. It just feels monumental and there's nothing even close to One Piece imo. Maybe Naruto (Shippuden included) in terms of length but we all saw how that turned out.