Some pie crust recipes use butter while others believe that Crisco or shortening is ideal. Butter is always going to give you a better flavor. Not only that, it's more sturdy and will make for a lighter, more flaky crust.  Shortening will give you a softer crust and can be good when making decorative elements because it will be less flaky; this can be beneficial to help your decorations or braided pieces hold shape better.