I don't like edgy characters but I DO like dark characters. Yes there's a difference that some people sadly don't know about.

DARK characters are characters who've been through things and use it to shape them. Dark characters, however, have some quality that makes them redeeming and interesting to read. Let's say we have a man who lost his family and was powerless to stop it. If he went around helping others while being grim and gritty, that makes him dark. Dark characters are well developed, well written, justified, aren't overshadowed be negative traits, and are likable. In a sense, dark characters are there to represent the dark reality of a story and how there's a relatable light in the darkness. 

An example of a dark character is Norse Era Kratos. Kratos is defined by his past servitude and how he seeks to better himself as a warrior and person overall. Even when he's in a situation where he doesn't want to do something, he accepts the burdens and completes the task all while offering wisdom to everyone. An example would be when he taught Atreus about rage and anger: "Anger can be a weapon, if you can control it." He's attempting to teach Atreus that anger is a motivator if used properly. 

Edgy characters are dark characters with trauma took up to eleven. Now there's nothing wrong with lots of trauma, it builds character. What makes them unlikable is how they act and think. Edgy characters are almost always underdeveloped, have no real personality, and just cringe inducing or infuriating. I read an isekai gamer dxd fanfic on Wattpad once, none of the popular ones and I can't remember the name. The guy had something called an "Ayanokoji mode", which allows him to not be manipulated. In truth, the guy just acted edgy so he didn't show weakness. 

Sauske and Todoroki are perfect examples of edgy characters, specifically ones all to common. Both of them have broken abilities (Sharingan and Half Cold/Half Hot) and just blame the world for their problems. Whereas Todoroki tried to mend his relationship with his father (I'm sure Sauske tried to reconcile with Itachi, I didn't watch all of Naruto), Sauske was willing to sacrifice people that WANTED to be close to him for power. They also try too hard to be too cool, which makes them unrelatable to their readers and watchers. They're also flawless, prodigies, or always has a reason for doing something edgy.

There's nothing wrong with a little edge, like making a tragic Necromancer or Dark Magician. But if you try to make them overly unique, bitter, and standofish, they start to become edgy. In layman's terms, execution for a dark character is everything. You can make a Sauske or Todoroki type guy and make them likable, it's all about how you execute them.