I am baffled every time I see someone say they don't like or that they hate S6. That's one of the things about this fandom I will never understand because S6 is the moment I really and truly started loving Buffy as a character. I mean, yeah, she carries the show from the beginning, and she's brilliant throughout it all, especially in S5, but S6 is when we get to see what Spike meant by "I've seen the best and the worst of you." We get to see that, and we get to love her anyway, just like he does.
How can you say you love a character if you refuse to see them at their rock bottom? She went through the worst possible scenario of her life. She was pulled back from heaven into hell, and she bloody acted like it.
I hated how she treated Spike, and I honestly wanted to hate HER for it, but the thing is, I could never. Because no matter how terribly she treated him, you had to understand where all that was coming from after everything that happened to her. I could never, ever hate her for anything she's done.
S6 is the moment we saw Buffy represent humanity in its purest, most tragic form. That's why I will always love it. It's the moment we see behind the mask of the hero who had to have it all under control. The hero who had everything and everyone always depend on her, falling apart like the human she is. She's being pulled under by all the expectations and judgment, and she's drowning.
Hating the moment the hero can no longer keep it together means we only ever see the cape and the suit, not the human under it. It's the same thing her friends do throughout the season.