The 9th.
Harold Schonberg in [The Lives of the Great Composers] said it pretty well:
[Here we are on a rarified plane of music. Nothing like it has ever been composed, nothing like it can ever again be. It is the music of a man who has seen all and experienced all, a man drawn into his silent, suffering world, no longer writing to please anybody else but writing to justify his artistic and intellectual existence.Faced with this music, the temptation is to read things into it in some sort of metaphysical exegesis. The music is not pretty or even attractive. It merely is sublime]
[But to the romantics the ninth symphony was the beacon. It represented everything the romantics thought to be the essence of Beethoven - a defiance of form, a call for brotherhood, a titanic explosion, a spiritual experience. The ninth symphony was the Beethoven work that most influenced Berlioz and Wagner.
It was the ninth symphony that remained the unapproachable, unachievable ideal of Brahms, Bruckner and Mahler. To the romantics, and to many today, the ninth symphony is something more than music. It is an ethos, and Debussy was not entirely wrong when he said that the great score had become a "universal nightmare". It pressed too heavily on the music of the century.]
Thanks, Mr Schonberg, you said it better than I could have,:) but the 9th is a fitting finale to the body of work that places him in perpetuity on the throne, which he may just share with Shakespeare and Michelangelo..............
