I enjoy three types of villains.
One, I enjoy manipulative villains who are major threats despite being physically or magically weaker than the protagonist, playing off their foe's weaknesses so well that their own true strength or lack thereof doesn't really matter. It's difficult to pull off, but way more impressive and scary to me than a villain who's wantonly tossing around overwhelming power. Anyone can make a chainsaw dangerous, show me someone who does the same damage with a toothpick.
Two, I love villains who are just very obviously having fun with it. Gog-Agog from Kill Six Billion Demons is the first example to come to mind. She's so powerful that she doesn't need to take things seriously, she can waste time on bullying her fellow Demiurge into letting her be all four commentators in a tournament and generally serving as comic relief. I tend to find 'evil-for-the-sake-of-evil' villains really boring, but when a villain seems like they might abruptly burst into a musical number despite the series not being a musical, I tend to find myself enjoying them a great deal more.
Three, I love villains who turn out to be pathetic. The main antagonist of Undertale spends your first two fights threatening you, insulting you, toying with you. But by the end of the third fight, he's revealed to just be a little kid, screaming and crying because "Why won't you just let me win!!!" Something just really gets me good about an antagonist who SEEMS all-powerful and cruel and sadistic... only for it to be revealed to be a mask they were desperately clinging to all along, and the real them is scared and weak and helpless. It's a delightful irony.
(Note that the 'arrogant noble bully' often found in isekai stories doesn't really do it for me. They're presented as pathetic from the first moment, quite obviously relying on bodyguards or fancy weapons. I want the cruel demon overlord who slaughtered thousands for his goal to be revealed to have gone senile and forgotten why he wanted so much power to begin with.)
