Ok I'll have a go...
8/ KGBeast, because Cold War nostalgia that's why.
7/ Preston Payne Clayface, because he doesn't want to harm anyone, but he kills everyone he touches...except the beautiful Helena.
6/Scarface/The Ventriloquist, just who is calling the shots anyway?
5/ Firefly, burn baby burn.
4/ Killer Moth, a Batman for bad guys, I can't help loving Killer Moth.
3/ Man Bat, because Man Bat is freaky.
2. Catman, especially after Secret Six, Catman has some edge and isn't really that evil which makes him interesting.
1/ Deadshot. Because the Ostrander run of Suicide Squad that is why...Floyd is awesome.
Also considered...
The Penny Plunderer because of that giant Penny in the Bat Cave.
The Ten Eyed Man because his FINGERS ARE EYES!
and Dr. Amanda Waller, but she is the hero and Batman is the villain...
8/ KGBeast, because Cold War nostalgia that's why.
7/ Preston Payne Clayface, because he doesn't want to harm anyone, but he kills everyone he touches...except the beautiful Helena.
6/Scarface/The Ventriloquist, just who is calling the shots anyway?
5/ Firefly, burn baby burn.
4/ Killer Moth, a Batman for bad guys, I can't help loving Killer Moth.
3/ Man Bat, because Man Bat is freaky.
2. Catman, especially after Secret Six, Catman has some edge and isn't really that evil which makes him interesting.
1/ Deadshot. Because the Ostrander run of Suicide Squad that is why...Floyd is awesome.
Also considered...
The Penny Plunderer because of that giant Penny in the Bat Cave.
The Ten Eyed Man because his FINGERS ARE EYES!
and Dr. Amanda Waller, but she is the hero and Batman is the villain...