I Will Remember You (1.08) makes me hurt more than any other Angel episode (excluding the scenes where my favorite ladies are killed off re: Cordy and Fred). This is mostly due to the last few scenes and the inevitable this-is-goodbye-but-not-really between Buffy and Angel. The worst part is that the pair are consumed by complete happiness - a level of happiness that isn’t repeated in either series.
If you follow the comic series (and I highly recommend IDW’s Angel: After the Fall a.k.a. Angel: Season Six) there are several intimate Bangel moments. But they are not nearly as raw as the scenes between Sarah Michelle Gellar’s and David Boreanaz’s characters.
Angel gave up his chance of a happy, normal life for her (and the rest of humanity, but, let’s be honest, mostly her).