Lotsa great choices but I would have to agree that Jim Morrison had a helluva lot going for him - except sobriety - and I will pick him as best.
And equally valid cases can be made for, among others: Dylan, John Lennon, Neil Young, Janis Joplin, Roger Daltry, Ray Davies, Albert Lee, Grace Slick, Sly Stone, Jagger, Iggy Pop, (name your favorite right here ).