I think "The Master" has a serious claim to being one of the worst villains ever on an otherwise very good TV show. I mean, he's worse than Buffy the Vampire Slayer's "Glory". He only ever has two modes of dialogue: horrible genre-savvy puns, and bursts of exposition delivered in between bouts of "manic" laughter. Seriously, the guy was PAINFUL to watch, but somehow compulsive, in the same way that "Batman and Robin" is compulsively watchable because you want to see just how bad it can get...
Although interestingly, he was actually a lot better in the Christmas special a year later. What happened there?
I got the weeping angels, the pick of the bunch; but then I'm not exactly a social butterfly. Should probably have taken Vashta Narada because I spend a lot of time in libraries, but what do you do?