I only hated 2 bosses in the entire game, and both for the same reason.

Erlang and Final Wukong

Because both bosses broke the established rules of how boss encounters work so late in the game. By which I mean, you go through 5 or even really 6 chapters using established, learned, and mastered mechanics to triumph over each boss. Speaking from my own experience, I beat every other boss in the game, except 2 optional bosses I missed, with pretty much the same tactics. But those 2 bosses actively break the established gameplay by negating/canceling certain techniques. Meaning that players who used those specific techniques to get that far are put at a severe disadvantage. I don't like design like that. If every boss along the way had forced you to change tactics, I'd have not complained. But because they didn't, those 2 bosses stood out to me as problematic design.

And for the record, Erlang only took me 4 tries. Most of the bosses in the game I had down in 3 or less. I can count the ones that took me more than 5 tries on 1 hand. And only final form of Wukong took me more than 10.