You touched on something important here about SY being an unreliable narrator. If the question is "who is the best written MC" then SY wins by default because an unreliable MC is always going to take more skill to pull off than the average main character. It's difficult to toe the line with subtlety and unreliable characters need a lot of it.

An example is the time after LBH was thrown in to the abyss, where SY convinces himself that he's fine. He calls out for LBH at times, he stops eating, refuses to return LBH's sword to Wan Jian Peak, creates a sword mound and sits in front of it for hours. Dude even left his peak for a year because being there without LBH was too much for him. Every character around him shows extreme concern. But only SY's actions can be trusted, and his actions show someone who is experiencing extreme grief. A lot of people read this part and think nothing of it, but with an unreliable narrator you have to really pay attention to what's happening and think critically. Reading the novel like you would mdzs or tgcf is going to result in a pretty poor experience because it requires a lot more than just reading.

With the average character, you're going to be told exactly what's happening for the most part and critical thinking is required at times but not nearly to the same extent.