Like I said on Gabriellabelle's LJ, I like that summary! Obviously it's not the whole story, but it's a good way to encapsulate it.

I love them both without reason, but I do think AtS is darker in a lot of ways. I've never been able to re-watch the last half of season 3 for example.

One reason I rearely bother to read "AH everybody human" fic is that the slayer/ vampireness is such an integral part of these characters. It's what makes the fluffy little cheerleader dark, but it's what makes her interesting!