Williams would be #1 in a world where Ennio never existed. But Ennio has the edge largely I think because of experimenting, getting that avante garde edge, playing with musique concrète, always adding to his tool box. That’s one of the great parts about watching that concert, you really get to see just how many tools he used. They’ve got a whole orchestra, and a chorus, and some rock instruments, and a whole bunch of crazy stuff in the percussion area (percussionists have the best job, they get to play all the weird stuff).
Unlike many other avant-garde/experimental composers, who I generally can’t stand, Ennio had an ear for a beautiful melody. He could weird you out and then make you swoon in love.
Very Italian in that regard.
I’d go with Bernard Hermann!