Theodor Adorno, that arch-critic of popular culture, once complained rather sniffily somewhere that the only thing that pop fans (he might have said jazz fans) liked of classical music was Ravel’s Bolero. No doubt because of its regular beat and easily recognizable melodic structure.
I do actually like it myself, as well as other Ravel and some Stravinsky, Debussy and Shostakovich. But by far my favourite classical piece is the Hungarian Fantasia by Frans Liszt. I just love the way the main theme is repeated in all sorts of mutated ways, taken apart, put back together again, etc.
So do others have a favorite classical piece, with some idea of why they like it? Dyed in the wool classicists, if there are any here, need not reply.