Lol secretly Elena. She probably hates both Damon and Klaus. I'll go for amon because he did something which directly hurt her: turning her mother into a vampire :)

she doesnt hate damon anymore

Yeah I was thinking she hated Stefan the most right now because he was going to kill her and she was sort of friends with him (huge slap in the face). I think she and Damon have sort of come to an understanding....

I think Damon

I personally think that she hates Klaus the most because of how much he made everyone suffer.
Then she hates the Salvatores most because of how much they hurt her. But I don't know who she hates more maybe Stefan because unlike Damon, Stefan claimed and still claims to be her friend.
I mean it's obvious that she hates Damon but at least she knows where they stand. Each time they meet Damon basically tells her that she's incompetent and that she sucks -__- so I thing she highly dislikes him but mostly don't give a damn about him.
Unlike Stefan, she thought he was her friend but he was never there to help her when she needed a friend. He only used her for Damon's plan or to protect Caroline and Elena, telling her that friends help each other but where was he when she needed comfort? He was dancing with Elena, wondering if apologizing to Bonnie for trying to kill her and for her mother's death, would make Elena happy :-/ I seriously wanted to punch Stefan in that scene, he's clearly no friend of Bonnie!
As for Elena IMO Bonnie doesn't hate her, she was just mad at her, but she still loves her.