I think Akito Sohma from Furuba is the best villain. Why? Well...
- he's the evil head of the sohma family.
- He treats Kyo like a monster just because he's the cat of the zodiac. (and even wants to lock him up because of it).
- He locked Yuki up in a room and tortured him both physically and psychologically every day when they were both younger.
- He is determined to make Tohru suffer as the zodiac members do (which is mainly because of him).
- He stopped Hatori's marriage with his true love and even blinded Hatori in his left eye :(
- He pushed Rin off a balcony.
- He kept Kureno as his own personal slave.
- He beat up Kisa and put her in the hospital after Hiro confessed his love for her.
- just about everything he does/did to the other Sohmas he did for his own selfish reasons.
- All of the sohmas are terrified to go against him because they're afraid of what he might do.
The strange thing is, Akito is still one of my favorite anime characters o_O He's just so angsty and evil, lol.
There are some other reasons why I think he's the best villain, but if I told them I'd probably spoil a lot of the series. So...
(And yes, I know Akito's "secret". everyone who knows what it is will prolly know what I'm talking about. I'm not saying any more to avoid spoilers.)