Shit even with my next to 0 knowledge about Makima or Blackbeard, their both probably still better than Yhwach. Biggest problem with Yhwach in my opinion is that he barely feels like a character He’s lacking in personality, his goals are poorly explained, he’s a massive hypocrite towards his own ideals where he seems to vaguely want what he thinks is for the greater good while being a total scumbag all the way through for literally no reason that even his own army has enough of it. Compare that to Sukuna whose a dick and makes no attempt to hide it but make it his defining trait. And while not too related to his poor quality as a villain, his powers are also just as poorly explained and frankly, boring. Madara and Sukuna, despite suffering similar pitfalls, at least feel like actual characters the story more then fleshes out so we understand them, their goals, what they want or look for, etc.