This is a difficult question. My head says Angel but my heart says Buffy.
I love Buffy for loads of reasons - I love the whole concept of the Buffyverse as it came to be in Buffy. I love the idea of the blonde walking into the alley with the threatening man and it being the blonde who walks out. I love the characters of Spike and Dru and their relationship, especially when they were first introduced. I love the guardianship of Giles watching over the younger characters. And I love the relationship between Buffy and Angel, and between Spike and Buffy. It's not because I'm a particular shipper or think there is something "destined" about either of the relationships, I just love the kind of the blonde girl fucking the vampire. So, I love Buffy for its earthy, physicality.
Angel is more restrained, I feel. For a start we don't see Angel in gameface even very often. They could have made a whole lot between him and various women, and yet they didn't. I like Angel. I appeciate it. Buffy I love.