I think, but also Xander, Joyce and Willow :)

In my mind, Giles made a great father figure for Buffy and Dawn. :) And it's a good thing too, because their own father, Hank Summers, soon became enstranged (another word for 'separated') from his family. It's too bad that unlike Tiana's father James from the 2009 film The Princess and the Frog, Hank had lost the love he once had for Joyce, Buffy and Dawn, and had lost sight of what is really important in life.

ANGEL

Or Willow. But she's got a great bond with a lot of these.

She's known Joyce her entire life (and Dawn too, I suppose, in fake memories), whereas with the Scoobies she's only known them from season 1 at the earliest. I'd say that she was closest to Willow from the Scoobies though.