Mine is "If you could read my mind". It tells the story of a man who loves someone so much he can't bring himself to tell her how he feels. If she could read his mind, he wouldn't have to. The only problem seems to be that the possible relationship that might have happened between them ended before it could start. (at least, that's how it seems to me)
It spoke to me when I first heard it and it still does now. Is it any wonder why it's my favorite?