I have been lost in happy practicing of three Debussy Etudes, works not heard nearly as often as many other famous 'etudes', for a variety of reasons, not the least of which is that they are quite challenging. My other happy-to-practice etudes, of course, are the Chopin, marvels of invention and beauty. And, here are two articles I have enjoyed reading that I think others may find interesting too (especially if you listen to the example attached!) The first one is called "Piano Practice from Czerny to Chopin", and the other is "Piano Practice Etudes for Intermediate Beginners". Both of these were found in Interlude. Hope you enjoy reading, and will be inspired to have happy practicing!