Alright, I'll give you one precious moment of pure, undiluted hatred, no problem.
Buffy
There are many moments in the show when Buffy drives me insane but what she does in the comics just takes the cake. I'm talking about the infamous what about me? line from "Turbulence". What Buffy's really saying is: all those years you were by my side, helping me not because you are a good person who wants to do the right thing but because you want me, you want to have sex with me and now when you've finally found somebody I can't kill I might give you a chance. This is the single most degrading line in the entire franchise because Buffy basically equates Xander to Spike, a soulless vampire. And you know what's particularly sad? She really believes that she still has a chance with this guy, never mind that she's not in his league, she expects him to dump and/or cheat on her own sister because she's suddenly interested. Can you get any more delusional than this? What an unbelievable bitch. See, nothing's changed, deep down Buffy's still a shallow cheerleader with emotional maturity of a stereotypical, brainless, horny teenager.
Willow
Again, many moments in the show but again, comics take the cake. Say, you have a best friend, you know her history, you know that her last uh...boyfriend tried to rape her and ever since she's been lonely, almost 3 years now. So anyway, your best friend goes to bed with somebody who is:
1. Not evil, homicidal, psychotic etc.
2. Alive
3. Actually younger than her, like, how is this even possible?!
What do you do? Naturally, you say something along these lines - Woohoo Buff! I'm happy for you hon, she's a nice girl and I'm sure she'll respect you. Sounds sensible right? Something a best friend, like Buffy in "New Moon Rising" for instance, would say, right? No, of course not. Willow goes all thinly-veiled lesbian biphobia on her because Buffy's apparently not gay and Willow, being an outstanding example of pure gayness is completely sure of that, I mean, it's not like she was all about men until she's met than one, special lady, you're born gay or straight, you die gay or straight, right, you gotta have a label and stick to it, right?
What a bitch.
Xander
"Into the Woods", 'nuff said. Riley cheated on Buffy, with a nameless corpse on the top of that and Xander acts like he wants his penis or something. Does Xander want his penis? If he does he could at least be honest about it. If not he's just a misguided dumbass.
Spike
Wait, Spike's not my favorite character, I hate that boring, lame-ass poseur. Oh well, every reason to hate Spike is a good reason, right? Two words - "Normal Again". Threatening an ill and obviously weakened person like he does in this episode is beyond disrespectful, it's disgusting and repulsive. I mean, what a sodding son of a dirt. And people say he loved her? Unbelievable. It's like...I hate Spike, that is all.
Giles
What kind of a watcher leaves his slayer when she needs help more than ever? The worst kind obviously, ladies and gentlemen it's Rupert Giles, the worst watcher ever. You know that Merrick would stay. He would offer his humble smile, do everything in his power to help Buffy get through hard times. Because unlike Giles, he was the real deal, the only real watcher she's ever had.