See I'll say my favourite is ATVS.
It just appeals to me more because it has that more adult nature.
It comprises different story narratives as well.
Season 1 was kinda like a Film Noir, season 2 went more musical. Buffy, though great, held the same line and though it dared go places on an episodic level, it rarely deviated on that.
Angel went far darker than Buffy, even though there were some really dark moments in Buffy.
Better in context of being made, i'm going to say Angel again.
We have some great character journeys in Buffy, mainly Spike and Willow BUT these are equalled by the development of Wes and Cordy and, as someone pointed out, this show was only 5 seasons.
Add to that the lead characters. Where Cordy and Wes equal Spike and Willow, Angel surpasses Buffy quite easily. Don't get me wrong, i'm not taking anything away from Buffy, I just felt we learned so much more of the Vamps motivations, his character past and to an extent where he will go that Buffy's kinda pales in comparison.
Angel, Wes and Cordy, though originally Buffy guys, did most of their growing on Angel.
We then have some great turns from Gunn, Fred, Lorne and even the likes of Lilah and Lindsay. These characters were far more compelling than some of the back ups on Buffy.
Yes we had Anya, Tara and Xander, Joyce, Giles and the season Big Bads that had some of the great episodes, but sometimes these guys had this kind of saccarine feel.
We have the likes of Darla that made a fantastic impact on the show, one off characters like Jheira, Gwen(couple off), the telekinetic girl that was abused by her father and the wonderful 'Anne', I think its easy to see why I believe Angel is the better show.