I'd say Xander and Anya, and it was torture watching it a second time with others (it's too painful to watch). But for some reason I find myself really ticked off at Anya right now. Xander, too, for obvious reasons, but Anya never regretted her history of vengeance, and when someone gets vengeance against her (much less than what she herself dished out) then she cries herself a river. I can't stand people like that (my mother was that way so maybe it's a bit personal). That just makes my sympathy for her dry up, and I feel as sorry for her as I do Willow when Tara leaves her (as in, not).
It's unusual for me to hate or despise a character and I'm sure it will pass (because I usually don't feel this way about Anya and not sure where this feeling bordering on hatred for Anya is coming from all of a sudden), but as we've got plenty of people on BB willing (maybe even driven) to spew bile on characters that many others love, I figured I'd share of my sentiment here.
So I'll guess I'll have to go with Oz/Willow, even if I have to accept that if Willow was truly gay then it was doomed anyway and should've happened sooner.
You know what, I'm gonna go with Cordelia/Xander, though my sympathy is reserved strictly for Cordelia (who also got impaled, as well as her giving up so much for him, letting her defenses down only to be hurt like that). I guess Willow (who is gay and hates Cordelia, and hurt Xander would go with Cordelia when he ignored her desire to be with him) got her revenge after all, as well as finally feeling more desirable than Cordelia. Just because I seem to be in an odd mood (and about to go to bed) I'll wait until tomorrow before I actually make a choice in the poll. If I still feel this way tomorrow then I'll click "other" (assuming I remember to come back to this thread).