First thing's first: I'll stop bashing Snape when someone gives me a valid argument as to why Neville Longbottom, whose parents were tortured to delirium by someone who didn't die till Deathly Hallows, feared that greasy man-child more than anything else in the world. Snape bullied Neville, Harry, Hermione, and anyone else he didn't like. He was, from an entirely objective standpoint, a bitter, jaded jerk.
If you're a movie fan only, I can kind of vaguely understand how you may not see the depth of Snape's general awfulness. The movies left out so much regarding his younger years, but I'll give you a short synopsis of why he's the worst(TM). He called Lily, the supposed love of his life, a mudblood - which is, might I remind you, probably the worst thing you could be called in the wizarding world - then defended himself by saying that she alone was better than the other muggleborns.
As if that made it any better. When his friends used dark magic on Mary MacDonald, who was most likely a muggleborn, he defended them, and compared that behavior to the pranks that the Marauders pulled. He actively tried to get the Marauders expelled from Hogwarts.
He dropped a tree branch on the sister of the supposed love of his life, and he got Remus fired for being a werewolf, and he insulted Hermione (a child!) after Draco caused her teeth to grow, saying that he didn't see any difference. That's frankly just the tip of the ice-berg.
People compare Snape to James all the time, which is just wrong for a number of reasons. James was a jerk as a teenager, but he changed for the better, and he confronted the Dark Lord himself without a wand or any means of defense to protect his wife and child. He joined the Order of the Phoenix as soon as he left Hogwarts, and he was never part of a wizard hate cult for any reason.
Severus Snape hated muggleborns. He thought they were inherently inferior, and he called his only friend a mudblood. He told Voldemort about the prophecy because he was entirely okay with an infant being murdered, and when he found out that the infant in question happened to be Lily's son?
He asked Voldemort to spare her and only her, disregarding how she'd feel about the loss of her son and husband. I have to reiterate that he bullied Neville until he was the poor kid's literal worst fear, and that occurred before Neville was thirteen. He also threatened to kill Neville's toad with a failed potion because it was brewed incorrectly. Overall, he used his power as a professor to make the lives of students entirely miserable. Students weren't even his only victim, because, as mentioned earlier, he got Remus fired.
But Snape helped Harry in the end! He loved Lily! James was a bully, too! Harry never asked Snape for help, and if Snape genuinely loved Lily, he would have done right by her memory rather than abuse the only thing left of her. James was a bully when he was a teenager, but he only made it to the ripe old age of twenty-one before dying because of Snape's actions.
Severus Snape was a bully, plain and simple. He part of a wizard terrorist hate-cult, but people act as that can be excused because of a half-way done redemption arc that he quite frankly didn't deserve. He's treated with admiration that other characters in similar positions could never get.
While Draco Malfoy is regarded as being beyond redemption by JK Rowling for things he did as a teenager, Snape is loved in spite of awful things he did as an adult. Don't get me wrong, he was a wonderfully written and complex character, but we as a fandom need to grow up and idolize better characters.
This is my hill, and I will die on it.