stefano because even though he does all these evil things, he has warmth and charisma and tons of presence. His scenes with his children were always great.
victor is good too as a villain. The problem is they made him weak these last years and now they're writing him as an ideal villain: cold, mean but with depth and capable of sincere love (caroline, philip).
larry welch was the funniest villain. i don't want him back but i liked him a lot when he was on last time.
female villains: vivian alamain, i miss her badly.only her could defeat stefano and kate. she was so fun and crazy.
it took me a while but i'm a sami fan now. it's time for her to stop humiliating himself for a man and go for world domination.
as you can see, villains are my favorite characters in soaps.I don't like the annoying, obnoxious ones like Chelsea, the first Jan (she was funny when played by the other actress) and Cassie (but i liked her with jack during the island storyline).