That is a very strange idea; where does it come from? I’d have said the moral superiority of Atreides over Harkonnens is overwhelmingly obvious, including to in-universe third party characters (e.g. Count and Lady Fenring).
Herbert, as I said. See:
http://www.jacurutu.com/viewtopic.php?f=17&t=2692
http://www.jacurutu.com/viewtopic.php?f=17&t=2690
http://www.jacurutu.com/viewtopic.php?f=17&t=2691
Herbert, as I said. See:
http://www.jacurutu.com/viewtopic.php?f=17&t=2692
http://www.jacurutu.com/viewtopic.php?f=17&t=2690
http://www.jacurutu.com/viewtopic.php?f=17&t=2691