"Broccoli or asparagus?"
"Math or Social Studies first?"
Kids don't get much real choice in life. One way I help my students develop their own sense of personal taste is to let them choose some of their pieces.
I use Piano Town with all my beginning students so they're already on a clear pathway built of steady, incremental steps. As they progress, I find ways to let them choose at least a few of their own pieces. One way I do is this is by using the Essential Piano Repertoire series. Because the pieces are carefully graded, I can give them a choice and know that I won't be asking them to do anything more difficult than I intended. I ask them to listen carefully to the CD and see which pieces they like the best. Depending on their ability I give them a choice of a few pieces or the entire CD. Sometimes if I'm feeling particularly mischievous I will tell them which piece they must avoid. (Usually it's the one I really want them to learn.) When they inevitably pick it, I'll make a fuss that it's either too difficult and I'm sure they won't be able to play it. They'll beg, beg, beg and we'll both get our way.
Students need choice, not complete control. I help them pick from meticulously selected choices. I don't hand them the complete Rachmaninoff Etudes and a Piano Town Primer Level Performance book and expect them to make a choice.
I also like the idea of letting them pick repertoire based on what it sounds like. After all, I choose to play a piece because I hear a performance which inspires me. Here's an example of a performance I listen to over and over again. (Martha Argerich playing Rachmaninoff Third Piano Concerto with Riccardo Chailly) Why would we think kids wouldn't be inspired to learn something they've heard? It's not always that they specifically want to learn the theme from Star Wars, it's that they've heard the theme from Star Wars. They associate the Star Wars music with something they like.
I go ahead and buy the book and CD for the student before I start this process. Kids love to get new books, and ones with CD's of the actual music they're going to be playing are a special treat. Now my recordings of all the standard teaching literature are available for instant download, so there's no excuse for not using them to help your students. Here's a link to 340 of these recordings to give you an idea of what's available. Yes, there are lots of videos on YouTube, but they are often quite inadequate student performances that won't do much to inspire your students.
Give them a recording and see what happens. It's always surprising. I'm always happy I did it. I hope you will be, too!