It hard to choose really. I mean, surely nothing from Schumacher's movies. Schumacher's villains were completely one dimensional and just over the top to that. One dimensional is perfectly fine, but at least do something that isnt so completely OTT. Two Face only cackled and giggled and acted like a ******ed cousin of Joker. Riddler was a ultra flamboyant homosexual version of Joker. Mr Freeze was just a comic relief and one liner king, even tho they gave him a great backstory. Poison Ivy was just a weird woman who was talking as if reciting poems. Bane was just a muscle (even tho he looked cool imo)
Now, Joker was also one dimensional, but it was just pure Joker that I knew at the time from 80s comics, and Jack's always entertaining. As the old saying goes, "Jack is interesting doing laundry". Catwoman was such a phenomenal character with split personality and fractured heart and psyche, and Penguin was a poor old dumb schmuck who was just continuously being kicked in the butt by life, time after time, all his life. Its a tough choice between Penguin, Catwoman and Joker