Shit.. good topic
I dont really have one as such because i can love a song and if i listen to it again and again i can get kind of bored of it.
I would have to say 2pac "Keep Your Head Up" i just love how the track kicks in and it still sounds fresh to me to this day. Specially when the volumes turned up, its a pretty emotional track listening back to it now.
I know its probably not the greatest track ever but its got something about it.