Novel with really good villain, better if villain have better thinking and schemes than mc Even better if mc have or the villain don't have plot armor
If your okay with original novel’s than Zombie Knight has some of the best villains I’ve ever read about. https://thezombieknight.blogspot.com/p/blog-page_19.html?m=1
Hisoka from HxH is probably my favorite villainous character. Even after teaming up with the MCs, he still has that deviousness that makes him an enemy. And yet...you can't hate him. He is a pretty cool enemy character and always has a few tricks up his sleeves
Trash of the Count’s Family <- Well it's a little bit else, the MC is a random guy who got reincarnated as a low grade villain from a novel and of course he wants to live without getting beaten up by the story's hero... but it's definitely worth reading
Hmm... Forty Millenniums of Cultivation and Transcending the Nine Heavens have strong, conniving villains. But my for the most badass villain that rules the story he's in, I'd go with the Coldfire series by C.S. Friedman. Gerald Tarrant is one of my all time favorite book villains. He is the boogieman of his world. Smart, insidious, and coldly cruel. Hell the the series sets the stage with a flashback of him ritually sacrificing his family for power. Wife asked him why he's killed their sons, why he's killing her. She though he loved them. Gerald, "I do love you. If I didn't....this would have no power."