Beer - Any type will work, but the flavor will be present in the bread, so use a beer that you like to drink. The alcohol cooks out while the bread bakes, but the flavor will remain. I like an IPA but a lighter pilsner or lager works great too. My kids sometimes dislike the slightly bitter flavor that comes from an IPA or more bitter beer, so a beer with a more mild flavor is certain to be more crowd-pleasing around our house.