Van Morrison.
In my top ten list also. Not a great voice, if you consider that alone. But I find that I always enjoy listening to the great singer-song writers -- Van Morrison, Bob Dylan, Joe Jackson, Elvis Costello, Willie Nelson, Kris Kristofferson, Johnny Cash, etc -- more than dedicated singers. The latter sing because they can sing, the former sing because they must sing in order to tell the stories they've written. All these men have vocal limitations compared to the best professional singers, but somehow they sound "better" to me for some difficult to define reasons. Passion? Earnestness? I don't know exactly.