As special as his 9th symphony is, and it is unironically one of the best pieces of music ever written, I have always preferred his 3rd Symphony, the Eroica Symphony. It's a grand, sad symphony that marks the start of the Romantic era of art (specifically in music in continental Europe and Germany). Written initially in dedication to the triumph of Napoleon; celebrating his heroic (Eroica is Italian for Heroic), revolutionary virtue and victories utterly humbling the Hapsburgs at Marengo and Ulm, to his creation of the Confederation of the Rhine and his restoration of the so-called "German liberties" which had been curtailed by the electors and princes of the Holy Roman Empire and the Hapsburg domination of German since the 30 Years War, ultimately Beethoven re-dedicated the symphony and rewrote the final movement as a funeral requiem after Napoleon declared himself Emperor and severely curtailed German political independence.
Wonderful piece of music, highly recommend.