1 - Xander & Willow - Just an unbreakable and long friendship since they were children, the scenes between W&X are just sweet (The replacement, Becoming, Grave, Empty Places).
2 - Angel & Fred - Just sweet, I love that Fred considers Angel as a Hero and has such admiration for him (AHITW, Hearthrob, Fredless)
3 - Buffy & Willow - Great friendship, Willow & Buffy confides in each other, talk about boys, secrets plus Willow restores Angel's soul for Buffy (Becoming, Choices, Same Time Same Place).
4 - Angel & Cordelia - I love them together in friendship, they help each other when they are not happy or not in a good mood (Judgement, That Vision Thing, Hearthrob, You' re Welcome, Billy).
5 - Xander & Buffy - A little tamed to me with Xander's betray about Angel in Becoming or his comments in S3 but this relationship has some great moments between them, in the end Buffy & Xander love each other (The Freshman, Seeing red, Dirty Girls, Graduation Day).
6 - Gunn & Wes - They are great together in ATS S2 (Epiphany, The Thin Dead Line).