Favorite Major Villain:
Ibara
Tbh, I didn't expect liking him from his intro, the setup to the village was Hollywood-esque. But, the cautious schtick definitely appealed to me. Each time, I underestimated him, he surprised. He was very entertaining and able to think on his feet, and I liked how he was able to quickly rebound when it seemed the tables turned and some funny facial expressions.
Tsukasa is the runner up, he made the best initial impression on me. Strong, charismatic, and perceptive, a good early antagonist. I don't hold his subordinates defecting against him because I see it as simply a far better alternative was presented to them. I mean US, technology, and Lillian, even with it being a wishful thinking, it was a shot they had to take considering the conditions they were living in, though I believe no one died yet (excluding the guys sent with Hyoga). However, Tsukasa was unable to pick up on the red flags from Hyoga and his final confrontation with Senku also doesn't measure up with those that came after him. Also, with the introduction of machine guns, I'm reminded of the boss when you face him vs. the boss when you unlock him as a playable character meme.
Least favorite major villain:
Dr. Xeno
I do like him, his science talks with Senku are great and that panel of them side by side around chap 155 or so is one of the best in the series. My qualm is more toward his goal as despot, and it being the source of the conflict between his group and KoS. Despite that, the chase and final battle are the best in the series imo.
Favorite Minor Villain:
Hyoga
My overall favorite villain, immediately sticks out with his design and fighting style. And his goal of making a superior gene pool is the most interesting to me in the stone world. I'd have liked to see that play out. And he remains the most interesting of the antagonists to join the KoS. His initial thought process always differs from the main group on how to approach situations. He has proven his loyalty to them and vice versa, but still something to keep an eye for.
Stanley is the runner up, I see him as The Winter Soldier of the series haha. He's proven himself on several fronts, though one area I'd have liked to see is his skills in cqc, like him being temporarily disarmed by a trap, and having to face off against the best of the KoS before reaching Dr. Xeno.
Least favorite minor villain: The popular choice
Mozu
Though not for wanting a harem, cause I mean in the context of a post-petrification world and their civilization, what more can you expect from the bad guys. It's more cause I knew he wouldn't be Tsukasa or Hyoga level, proven by Hyoga putting him on his ass once he got his proper spear.