Okay first of all Desi Buxton, I see your point, yes Snape was rude to Lily in their fifth year but if you read Deathly Hallows you would know that the night after he called her a so called mudblood he was sorry and begged for her forgivness. Second, Snape didn't just have a crush on Lily but was in deeply in love with her. We see this when he cast a patronous it took shape of a doe which was also Lilys patronous and in the magical community when you are in love with another witch or wizard your patronous takes the same shape as theirs. And how you said Snape helped a little bit is not true. He literally protected Harry during his time at Hogwarts. And while he was a death eater he was still loyal to dumbledore and he gave information from voldemort to the order, helping the order get the upper hand during harrys fifth and Sixth year.
And so I actually answer the question Umbridge because of her crimes against muggle borns or so called mudbloods, taking mad eyes magical eye, and hurting Harry, the hero of the story.
I mean come on we all know we hate Umbridge more than Voldemort.
And Bellatrix Lestrange because she killed sirius black who was harrys fatherish figure. Um lets not forget her touturing hermione and killing Dobby and killing Tonks. Well at least Molly Weasley killed her.
And all the death eaters except Regulas Black and Snape. Grindlewald. Voldy. Reason should be obvious