It doesn't matter the genre. If a song makes me want to laugh uncontrollably and weep at the same time, it's a ****ing good song. Many fit the bill for a variety of reasons, but it's as if you reach a spiritual moment where the music and your soul are in sync. It's a beautiful thing.
Well... Song length: Short NO, Long YES PLEASE, Solo VERY YES Catchy Guitar Riff VERY VERY YES Jack Black-ish Falsetto YES Songs Stuck In My Head. NOT GROSS HANNAH POOPTANA OR JONAS CRAPPERDS. ANYTHING ELSE: YES Epicness and Win YES (Epic by Faith No More, Lookin' at you)
I personally feel that the instrumentals of a song is what makes it come together. Although I am a guitarist, if the drum beat sounds like it is catching up all the time or the bass line isn't flowing with the drum track enough it just sounds like nails on a chalk board.