I am team butter, because it has the best flavor and turns a beautiful golden color. Some argue that because the butter’s milk solids can burn, it is better to use oil, but I have not had any issues with an off taste in my turkey, even when I start it at a high temperature. If you’d like to be 100% safe (and go above and beyond), you can brush your turkey with clarified butter, which is butter with the milk solids removed.