User blog comment:B214/Volume 22 spoilers/@comment-73.46.6.122-20160819203110/@comment-154.242.38.77-20160819230022

One of the four mentionned "Rookies" there's only Sairarog who's suited to become a Maou, The fact that there's 4 young devils who are training their servants and the fact that there's 4 Great Satan is purely a coincidence, therefore it's not enough as a proof to say that each one of the four would take a throne and become a Maou, Rias, Seekvaira and Sona are weak and can't possibly reach the Maou-class in term of power, Sona and Seekvaira have talent in other departements other than power but to become one of the rulers of the Underworld, a symbol to people, Power is required, that's why from my perspective only Sairarog is suitable to become a Maou, because he's strong, cherished by his own people and has 'that' charisma of a Leader like Sirzechs had.