nah man primogeniture all the way, otherwise agnatic open (turkish succession) and in some cases, such as being in jimena spain or rurokovich russia, go for seniority. gavelkind kinda sux but its the default option :P worst of all is ofcourse elective -_- which i recommend never to use unless you really want to do some serious roleplaying :P well.. it can come in handy if your son is like a total retard but killing him would be easier