Which do you prefer of these seasons?
Season Four of Buffy or Season One of Angel
Season Five of Buffy or Season Two of Angel
Season Six of Buffy or Season Three of Angel
Season Seven of Buffy or Season Four of Angel

For me, its...

Season One of Angel, I love Doyle and the stand alone episodes of this series. I also liked the fourth season of Buffy, but Angel gets the edge.

Season Two of Angel, I loved the second season of Angel and only liked the fifth season of Buffy.

Season Six of Buffy, this is where I prefered Buffy to Angel. I liked Angel's third season, but Buffy's sixth was really great.

Season Four of Angel, The fourth season is probably my least favorite of Angel, but I still prefer it to Buffy's final season.

Season Four of Buffy The Vampire Slayer, over Season One of Angel (this was an overall weak year for both shows IMO).

Season Five of Buffy The Vampire Slayer, over Season Two of Angel.

Season Six of Buffy The Vampire Slayer, over Season Three of Angel (though both were excellent that year).

Season Four of Angel, over Season Seven of Buffy The Vampire Slayer (Angel's fourth season was really interesting, while Buffy's final season wasn't that great).

4 of Buffy over 1 of Angel.
5 of Buffy over 2 of Angel (a terrible season IMHO)
6 of Buffy over 3 of Angel (ditto)
4 of Angel over 7 of Buffy (Angel finally steps up to the plate and not before time. Easily it's best season.)