It's common courtesy to the next band director that takes over.

Speaking from experience, there is nothing more stress inducing than walking into a program in July that does not have a show lined up. Also, you know your kids best. You can plan a show that they can be successful with. Someone new that walks into your program is going to have some difficulty finding something appropriate for your kids after barely meeting them.

If the next director really doesn't like what you picked, he/she can always change it, but it's better to have something rather than nothing.