I think it goes without saying that there is no magic formula to creating the perfect song. Even if there was, someone somewhere would hate it to no end, and would wax the demerits of this otherwise amazing composition to try to ruin it for the rest of us. Simply put, everyone hears a song differently, and no song means the same to everyone who hears it.
Most people associate specific pieces of music with certain emotions, emotions that are generated spontaneously by the viewer during the moment of hearing the song.That doesn't mean the emotions are random; rather, a song with an intended or implied effect will not affect nor change how an individual uses a song to form cognitive memories. Someone hearing the Beatle's "Yesterday" after being accepted to a prestigious university may remember the song differently than someone who hears it en route to a funeral.
What I mean is that there isn't a single song that can encompass every emotion capable, but rather we as humans use individual pieces of music as recall tools to link our memories to either an event or emotion. This bond succeeds the event, using our natural sense of hearing to permanently bind sound to memory.
There is no single perfect song. But, there are many songs that are the best, because it is all relative. Next time, I'll let you know why Al Steward's "Song on the Radio" is the best song.