How do you decide the heir to the pack?

I usually choose those who have been very close to me since they were puppies because I grow more attached to them. But I also observe whether they are sociable, good hunters, and defend the pack without hesitation. In my main pack, the heir was chosen based on these factors, and besides, he was always very present in his mother's life; whenever she went on excursions, he would go too. I think in her entire life (eight years old), he only missed her three times. He's from her first litter, and it just so happened that his attributes were good. He's my favorite of all the children she's ever had. Sometimes I'm unsure which will be his next heir, whether to base it on personality, attributes, or the oldest. How do you choose?