I don't really have an definite favourite, but I've never thought that a villain in One Piece was lame from a character POV.
- I villain which I have truly hated would have the Akainu, he just has a blackening aura which makes me dislike him.
- The villain which got under my skin and who I really wanted to see get beat up the most was Bellamy. But Luffy sorted him out
- If I had to pick, I think my favourite villain (if you can still call him one) would have to be Buggy

. Just everything to do with Impel Down and Marineford which involved Buggy made me crack up. Soooo much Luck!