The Hunt
Hunting is more about the hunt than it is the capture, at least on Angelus' part. He considers it a sort of foreplay. Flirting, if you will. But the prey has to be clever, at least smart enough to know she's being hunted.
Drusilla was. Oh, her visions warned her of him, told her to seek shelter in the safest place possible. Too bad it wasn't safe enough.
Hunting Buffy is even better. She's harder to break. She won't come to him willingly. She'll come armed with a stake, a cross, holy water. Her own will to survive.
Angelus isn't sure if he can bend her enough to make her brittle, to bring her close enough to snap. But it'll certainly be a pleasure to find out.