I fully understand why people hate Sasuke from the point after he meets Obito, but before that he was perhaps the single most interesting and well rounded character in the entire series. Everyone either calls him whiny and emo, spoiled and weak, evil and monstrous... or greedy. None of these fit, at all.
He was broken from the loss of his entire family, tortured by his older brother and driven to total isolation by his path and his pain. He strove to be the best because unlike Naruto and all of the other characters, he had a goal and a lot to lose if he failed. It was the one thing that stopped him from falling into despair. Unlike Naruto his goals have foundation, and he works to build his own skills through training and doing anything he needs to make it a reality but even then he keeps his humanity and doesn''t kill Naruto. He goes to Orochimaru to actually achieve the goal he may very well lose his life to because his family deserves to be avenge for their unjust killing ( In his eyes with what he knows).

Even afterwards he didn't kill until his mind snapped, learning from Obito that his goal was not only forced ( Itachi's manipulation) but that the village that he once called home was responsible for the death of his family... a village that forced the Uhciha into a corner, then killed when they lashed out for their own sake and stole their eyes as a final fuck you...

Yeah, before he gets power from the Sage he earned every ounce of powe, Training his body, going through experiments to strengthen his body and make himself immune to poisons, mastering fire and lighting jutsu and making several of his own including an S rank jutsu that is outright badass... he learned and mastered sword play and became incredibly able with genjutsu and weapons. Even when he killed Itachi he earned his Mangekyo through that very battle and later reearned his Eternal mangekyo since he not only beat Danzo but killed Itachi to begin with so they are his spoils of war. He mastered their abilities over time ( Months) and still could use all he had before.

Sasuke was interesting well rounded and just a better character then practically anyone else... until he wanted to be hokage and was given more power from the sage which made him annoying... like naruto. Honestly even his drive made more sense, he had a clear goal that wasn't solely for attention or to get acceptance but was for his family and self and was something he always strived for. He actually did something to acheive his goal, he didn't wait around for it to fall into his lap unlike Naruto. He had a reason for his beliefs, something Naruto never had.

The worst thing the series did for him was bring him back to the leaf, he had his own beliefs and they stole that to make him a Naruto clone like everybody else who Naruto fought...

Why is he then reduced, in fanfic, and in most conversations to a whiny emo with a hunger for power? He had a purpose that defined him and like his charecter or not, that was something to respect...

He wasn't wrong in wanting the Kill the Kages, since they were as much the problem as they were the solution. Hell he might have even been a decent Kage, where as Naruto is too naive and honestly was handed most of his power...