My favorite songs span a wide spectrum, from the Kinks to Neutral Milk Hotel to Enya to opera. But the genre that probably affected me the most is glam rock especially Bowie and Roxy Music. I clicked on a catchy, hummable melody as being most important, but it actually isn't really necessary to me that the melody be catchy and hummable (although a lot my favorite songs do have this), just that the melody has to somehow affect me. Somehow the notes sound just right.