Cordelia behaved like a calculative politician underneath her pretty face, beautiful body, fashion sense, and charisma that dragged on. It impressed me none. What the "Angel" show writers did to her character development was unspeakably shameful.
Willow was transforming into a victim complex rather than taking accountability until it bottled up inside of her so much. Albeit, she improves after that.
Dawn is treated as an additional character without necessary writing to make her truly shine when writers focused on Buffy, Spike, Willow, Xander, and villains instead.
Faith would have had potential if she displayed redemption of her actions towards male characters like Xander and Riley in "Buffy the Vampire Slayer." Not that I am talking about the "Angel" series regarding her path on redeeming herself.
Tara should have been fleshed out more thoroughly. I felt like she was only there because of Willow vicariously. Not on Tara's own volition.
