I see what people are saying about Boreanaz not being a great actor, but I thought it added to the fact that Angel was socially awkward so it seems a perfect fit. Himself and Buffy had great chemistry in the early days. I switched my allegiance from Buffy (show) to Angel (show) when Angel started.
Thought 'City of' (Pilot) episode was a great start. Buffy went downhill after
1) Angel left
2) Giles took a back seat when they went to college
3) her Mother passed (which was v. well acted to be fair)
4) Spike became a whipped b*tch
5) and worst of all... Dawn appeared. That ruined the show for me.
While all that was going on Angel was going from strength to strength. It wasn't without it's faults obviously but IMO it was superior to Buffy as the two shows came to a close. I should say I still loved both shows!