The attribute of God that we think of first is usually holiness. Holiness means other, distinct, separate. It is a master attribute of God in that all of His other attributes exist in conjunction with this attribute.
God is holy in His love. He is holy in His mercy. He is holy in His justice. He is distinct and not like us in any of these things. He is holy, holy, holy.
I think the attribute of God that I think first and foremost of when I think about the attributes of God is His holiness. Many have said it long before me that holiness is a master attribute of God. What does that mean? It means that all of his other attributes exist in conjunction with this attribute of holiness. Holiness just means other or distinct, separate, and So God is loving, for instance, that's another core attribute of God.
He is holy in His love. He's holy in His mercy. He's holy in His justice. He's other, He's separate, He's distinct. He's not like us in any of these things.
So the perfections of every other attribute are really called out in His holiness. He is holy, holy, holy.