All 4 of them added something distinctive to the song which makes it so memorable; it's arranged with contrasting type voices, which I think makes it such a nice experience as a song. Al isn't the best singer, but he kicks the song off well with the light, high voice. Then, Mr. Ingram comes in with something deeper, fuller and more soulful. Next, Barry and El were very nice contrasts to one another with their falsetto and bass voices. Literally none of these men did a bad job. It's hard to choose the best because they all owned their verses.