Can anyone please source or substantiate the emboldened phrase from Reddit?
As others have already said, the worst piece is probably something obscure that is not performed or recorded. But if we are going by relatively well known pieces by relatively well known composers, I might go with Boulez' Structures. I am a big Boulez fan, and love almost all of his pieces, including some of the more aggressive early serial works like the 2nd piano sonata and the Flute Sonatina. But Structures just doesn't do anything for me, there doesn't seem to be anything to grab on to (which may well be the point of the work). I think even Boulez himself had stated that he didn't feel the piece was successful. [I bolded.]