A Good Steward of Papal Primacy
The fifth-century pontiff was one who exercised his authority decisively, humbly, and pastorally. He brought unity to the Church in difficult situations, but he never compromised the deposit of faith. Without a doubt, he earned the title "Great" because he was focused on protecting and proclaiming the faith of the Apostles.
On caveat: Pope Benedict seems to have nearly identical qualities to those he described about Pope St. Leo the Great.