Babe is the most realistic villain currently; she's layered and complex and weirdly inspires a twisted kind of sympathy even when she's being vile.
Claudette is fabulous, OTT and highly camp and works best in big, explosive scenes.
I don't think anyone else falls under the 'nasty' category apart from maybe Ronnie, though nastiness isn't her modus operandi, IMO. She only tends to do bad things when she feels under threat, which is pretty often to be fair.
Actually, thinking about it, Louise is pretty nasty with little in the way of redeeming features but I guess she gets a pass as she's young.