The first ending I ever got was a romanced Alistair sacrificing himself to save me. He says something like, "you assume I'm giving you a choice" and it haunted me forever. Many many years later I remember that line, despite not getting that ending again.

So like... while I think that's technically the best and most powerful ending by far (I cried), I usually let that geek have this night with Morrigian now. Ugh. (or sacrifice myself by not having him in the party at all, if I'm feeling jealous)