I would also like to add, the while I voted Angel, I probably liked seasons 1 through 3 of Buffy more than either show stand alone. My vote was kind of season 4-7 of Buffy versus Angel, since Angel was on Buffy for seasons 1 through 3. As a whole, I did prefer Angel because I really didn't like Buffy nearly as much after he left. I would however, take season 1-3 of Buffy over Angel.
I actually just finished watching Buffy and Angel for the first time a couple months ago. And I remember that I would have to force myself to stop watching Angel episodes so Buffy would keep up. I didn't have that problem the other way around. Thats what I am really basing my vote upon too. Admittedly Buffy was less serialized than Angel which probably let into the not needing to the episode, but I just remember being more excited to keep watching Angel.