Well Buffy is like so much hotter and the whole cast, the show really had one of the first solely female TV heroines, which so many other shows are trying to follow (Dark Angel, Alias, maybe 24). So perhaps if it isn't the best of that genre, it was the pioneer, and that should count for something. Plus Buffy was a lot of fun in the start, and was really something different, let alone sexay ;D . But as they began to run out of plots the story started to falter, and so it was a good thing that they finally ended the show.
I like Angel too, but it didn't really have as much appeal to me as i've seen it all before on Buffy. Even though the shows have their own differences, Angel really just didn't do it for me, even if it was probably a good show in it's own right.