Hmm.
Well this is something that changes especially as I discover new things.
I'll pick a quick range of 10 pieces I always listen to no matter how many times I have heard them.
Beethoven Op. 111, Op.57, Op.53.
Schubert D.946 - 2
Chopin Op. 47
Bach. BWV. 847, 851, 855...
Liszt "Auf dem wasser zu singen", "erlkonig"
But really, picking favourites is a futile exercise.