I think Where Buffy Kills Angel In season 2.

Pretty hard to top that...unless you cross over to Angel for 'I Will Remember You' or 'You're Welcome'.

Anya's speech in "The body" always gets me.

Yep, also sad. I think I've mentioned somewhere else Buffy's little breakdown to Willow in The Prom, bless her.

I think it has to be when spike has just returned with a soul and he and buffy are talking in the church. I thought that was an amazing piece of acting

I have to agree either anyas speech in the body or the gifts especially spikes reaction

It was a heartbreaking moment for me when Buffy is kissing Angel and both she and the audience knows that she has to kill him. Also when Buffy breaks down in the Prom and lays her head down in Willow's lap crying "Right now I'm just trying to keep from dying. I feel like I can't breathe, Will. I feel like I can't breathe."
But Anya's speech in the Body also moved me.

Passion! i mean jenny wasnt my favorite character but that whole episode just gets to you second would have to be Becoming, though lets just say most of season 2!

Of course the moment when Buffy kills Angel. You'd have to be made of stone to not be moved by that, Bangel fan or not (I'm not). But I also love the moment in Bargaining when Spike sees Buffy for the first time after she comes back from the dead. The way he looks at her just wrecks me. And when Spike dies...I cry every time. He's such a hero, hehe

yeah for me its where buffy has to kill angel it so sad oh and anya speech in the body makes me cry everytime (even though im bascially crying through the whole episode) and when spike dies

For me, it's the end scene of Beneath You. Or when Spike completely breaks down in the Gift.