This is an example of stupidity in the making.
There is no single composer that is both overplayed AND overrated, because for every piece that is overplayed and overrated, you will find another piece by that same composer that is both underplayed and underrated. In addition, almost every composer that is overplayed (meaning they have a lot of pieces that are overplayed- the composer
him/herself can't be overplayed.

) are actually
underrated, because people get completely sick of the pieces and stop recognizing them for the genius works they are. Beethoven's Fur Elise, when played by a truly masterful pianist, is still exquisite to my ears, no matter how many times over it is butchered. So is the 'Pathetique' Sonata. Mozart's Serenade in G major is another example (although I much prefer it when all 4 movements are played, rather than just the first.) Do we forget that these works are played ad nauseum because people LIKE them?
Furthermore, nobody is going to be in agreement on this sort of thing. It's not exactly a thing we can measure- how overplayed or overrated a piece or composer is. Someone who dislikes Chopin's works will post his name, thinking only of the Minute Waltz, the Etudes Op.10 No.3 and Op.10 No.12, etc., and someone who loves ANY of his works- overplayed or underplayed or neither- will refute the former. Same goes for every composer already mentioned here- Schumann, Schubert, Brahms, Mozart, even Phillip Glass, and the same goes for every composer which will, no doubt, be brought up later... (I realize I may be exaggerating reasoning for posting the certain composers, but hopefully you understand the general concept I'm trying to convey.

)
These types of threads never end well.
Phil