Webakaza is a typical villain you see in most of the anime with a sob backstory (nothing new and interesting).
Kokushibo’s character is different and interesting.
Webfrom its activation alone, kokushibo not only managed to blow away sanemi and gyomei but also slice apart muichiro, genya, the trees from genya's blood demon art rooting.
Webakaza being chastised by kokushibo.
Akaza's hatred for doma and kokushibo can be further seen when he loses his patience and destroys doma's head, after he asks to join.
Webkokushibo momentarily lost the will to fight upon seeing his brother's memories, stopping his healing;
Then again, even if he wanted to continue, genya's trees stopped him.
Webkokushibo and akaza (image via ufotable) kokushibo made a brief appearance in demon slayer season 3, but the impact he left was unparalleled.