Well, excluding the Theotokos, John the Baptist, and the Apostles I would assume that any list should include (in no particular order):
St. Basil the Great
St. Gregory the Theologian
St. Gregory of Nyssa
St. John Chrysostom
St. Athanasios of Alexandria
St. Cyril of Alexandria
St. Maximos the Confessor
St. Symeon the New Theologian
Other potential candidates would be some of those listed above by others, especially St. Gregory Palamas, Sts. Cyril and Methodios, St. Ignatios of Antioch, Sts. Constantine and Helen, Sts. Joachim and Anne, St. John of Dimascus, and others I'm probably forgetting.
Then, there's always the ranking found in a prayer in Orthros:
O God, save your people and bless your inheritance. Look upon your world with mercy and compassion. Raise the Orthodox Christians in glory, and send down upon us your rich mercies, through the intercessions of our most pure Lady the Theotokos and ever‑Virgin Mary; the power of the precious and life‑giving Cross; the protection of the honorable, bodiless Powers of heaven; the supplications of the honorable and glorious prophet, and forerunner John the Baptist; the holy, glorious, and praiseworthy Apostles; our Fathers among the Saints, the great hierarchs and ecumenical teachers, Basil the Great, Gregory the Theologian and John Chrysostom, Athanasios, Cyril, and John the Merciful, patriarchs of Alexandria; Nicholas, bishop of Myra, Spyridon, bishop of Trimythous, the wonder workers; the holy, glorious great Martyrs George the Victorious, Demetrios the Myrobletes, Theodore the Teron, and Theodore the General, Menas the Wonderworker and Charalambos the Hieromartyr; the holy, glorious, and victorious martyrs; the glorious great Martyr and all‑laudable Euphemia; of our holy God‑bearing Fathers; [the patron saint of the church]; the holy and righteous ancestors of righteous ancestors of God Joachim and Anna; [the saint of the day]; and of all your Saints; we beseech you, only merciful Lord, hear us sinners who pray to you and have mercy on us.