The One I Missed
Einstein wrote that the best musical audience is one that can appreciate Mozart's Piano Concerti, implying of course that Mozart's Piano Concerti comprise the best music there is. When I was a student I was fortunate enough to buy a box set of the complete concerti (in an Oxfam or other charity shop): I think it was Anda's cycle.
Since then I've lived with these works and heard them performed by most of the great pianists--Ashkenazy, Brendel, Bilson, et al. All of them--from the Jeunehomme onwards--are great works, though my favourites are K466 onwards.
Imagine then my disappointment that I missed the greatest concert of all time! It was of K466, the Dminor, in December 1794: the soloist was a certain Ludwig Van Beethoven. No matter that I wasn't yet born--I'm still disappointed that I missed it.