Sylvanas was, and perhaps still is, one of the most popular characters in the franchise, and this is a serious question. I've noticed in the past on the official forums and Reddit, that LOTS of active players, especially younger female players, seem to always defend and admire her, even after the Burning of Teldrassil.
Their reasoning was that she was a deeply traumatized female who was able to overcome and harden herself through her trials and become a strong individual with very great force of will - that she was able to assert her agency as a female character and leader, a hunter and a banshee, an undead elf and an iconic Horde character.
She was extremely beautiful and deadly and graceful, and yet she had her nuanced moments, such as her famous Lament of the Highborne scene, a very complex and relatable character to lots of young women and female gamers who admired her in equal parts for her tenacity and ruthlessness.
Even Patty herself stated in the past that she faced significant domestic abuse when she was a young girl, and she channels some of her inner pain and anguish into her voice acting, which is perhaps what makes it so realistically engaging and potent for so many people.
Of course, those against that perspective would be that Sylvanas was a strong female character, but one who started Azeroth's fourth global war and committed what most Alliance and night elf players at least consider genocide. Although - she has been "redeemed" somewhat, and is now relatively "whole" and complete, and feels remorse for her actions - I recommend her novel to those who did not read it, it was not perfect, but much better than many other books today.
https://www.amazon.com/Sylvanas-Worl.../dp/B08ZXZDNVS
https://www.youtube.com/watch?v=uxWw-6Ipyuc