The title 'King of Ace' in 'One Piece' is a hotly debated topic among fans, especially when it comes to the Straw Hat Pirates' first mate, Roronoa Zoro. While the term isn't officially used in the manga or anime, Zoro's role as the crew's strongest fighter after Luffy makes him a natural fit for this unofficial title. His insane durability, mastery of the three-sword style, and ability to push through near-fatal injuries—like taking all of Luffy's pain in Thriller Bark—cement his reputation.
What really stands out to me is how Zoro's growth parallels Luffy's. From his early days in East Blue to his recent battles in Wano, he's constantly evolving, like when he unlocked Advanced Conqueror's Haki. He might not wear a crown, but his sheer willpower and loyalty make him the de facto 'King of Ace' in many fans' eyes. Plus, that moment he bowed to Mihawk for training? Pure respect for the craft.