Weirdly, I think my most memorable moment is actually in the first episode of Angel: -
Cordelia: Oh, god. I'm sorry! I'm getting all weepy in front of you. I probably look really scary. I finally get invited to a nice place...with no mirrors...and lots of curtains...hey, you're a vampire!
Russell: What? No, I'm not.
Cordelia: Are too!
Russell: I don't know what you're talking about.
Cordelia: Hey, I'm from Sunnydale. We had our own Hellmouth! I think I know a vampire when I'm...alone with him...in his fortress-like home. And you know, I think I'm just feeling a little light-headed from hunger. I'm just wacky. And kidding! Ha, ha.
Coming to the whole thing very late (I didn't sit down and watch either series until after they'd both been off the air for some years) I already had a vague impression that Angel wasn't as good. That scene made me feel like it would be just fine.