Oh that's right on Jon's poisoning, isn't it. One forgets all the threads.
While Cersei didn't directly order Jaime to push Bran out the tower, she did indicate to him that he needed to do something about the situation, but she wasn't thrilled certainly with his solution, largely because Bran doesn't die.
Jaime has overall done more bad things than Cersei, but Jaime tends to be seen as less "evil" because he's going through remorse. While Cersei has felt remorse about a few minor things, she regards herself as justified in her actions, along the rationales that her father set for the family. For Jaime, it was less about justification than family and pride. Tyrion has also done evil things, but tends to be given a pass. He obviously has the most perspective on his own and others' actions and the most remorse. Cersei is currently in the series staging a comeback, but she's doing it by becoming the pawn of other forces, so we'll see what happens to her.
For me, there are many, many more much more evil characters in the story than Cersei. I wouldn't put her at the bottom, certainly, but in many ways she is not the badass she thinks herself to be, which is why she makes some huge mistakes.