I think property taxes are the only form of taxation that is moral. Income tax is a form of enslavement. Sales tax is suppression of freedom of expression. According to John Locke, natural resources become yours by mixing them with your labor, with the caveat that you taking possession does not preclude other people from taking possession of other resources. Since land is inherently finite, but we also want it to be held by the people who will use it most productively (as opposed to redistributing it equally), I would say a tax on it is fair, moral and just.