In Wano its definitely Denjiro
You can dislike Carrot or Yamato from the bottom of your heart, but Oda did something with them during the story. Ad frankly Carrot didnt tale that much spotlight during Wano.
Denjiro was hyped, meant to be important for a good part of the arc, to end as a completly background character and scabbards.
Kawamatsu was even more meaningless but his stakes and narrative was lot less important to be begin with. (I wonder why Oda crated Kawamatsu, the guy has like 0 purpose in the story)