Hello,
First off, are you trying to compete with this other pianist or share your talent? Seems like that's your main issue. If your trying to compete with him then take the more challenging piece but make sure it's in top shape.
If you want to show deep talent in music, perhaps do your composition or a very emotional piece that pulls in your audience. Keep in mind, you don't have to be fast and flashy to catch people's attention. Just do a piece that you know you can do an amazing job on. It is irrelevant what the other pianist will be performing.
Hope this helps. Feel free to message me if you have any questions.
-Benjamin Collison