This question could be looked at in a couple ways. First, which of God's attributes are above all others for Him personally? And second, which of God's attributes are above all others in regard to our understanding of Him and to ourselves as His children? Because God is perfect, every attribute He has is also perfect and could be counted as of equal importance to any other attribute. His attributes cannot be ranked as if some were more critical to who He is than are others. However, the manner in which our human minds begin to understand His attributes and how they pertain to our understanding of and relationship with God is important. Humanly speaking, the way we understand God's attributes comes in a certain order.
Are any of God's attributes above all the others?
The fact that God is perfect means that every facet of His being, every quality He has, must also be perfect. God's omnipotence, omniscience, and omnipresence, for instance, would not be possible on their own because in order to have one you must have the others. Therefore, neither being all-powerful or all-knowing or all-present is more important than the others. Every attribute God has is perfect, making them of equal importance and combining in a grand culmination within the One perfect and infinite God (Isaiah 6:3).
We, as humans, are far from being infinite or perfect in any way. This means that our understanding of God's attributes must come gradually, in bite-sized increments. We need to understand certain elements of God's character before we can progress to the next level of our understanding. A base level of understanding God's character as a human being is understanding His perfection and His holiness, and how strong of a differentiation that creates between God and man (Exodus 15:11). When we understand this primary difference, we are better able to grasp His other attributes and understand how He is capable of possessing them.
Think about it like this: we have to develop an understanding of God's exclusive-to-Him attributes before we can truly understand His attributes as they relate to us. In order to understand God's qualities such as His justice or His love for us, we must first have a foundation that understands and therefore affirms His holiness, omnipotence, and sovereignty (Psalm 115:3; Psalm 103:19; Romans 9:18). For it is from these attributes that the others spring forth. It is when we learn of God's foundational attributes that relate directly to Him being God (holiness, sovereignty, etc.) that we are able to have a proper understanding of the attributes related to His personality (love, justice, kindness, etc.) and how He extends these attributes to us.
The attributes of God, what are they?
What are some of the key things to know about the nature of God?
Is God a person?
How does the Bible use anthropomorphism to talk about God?
How is God eternal?
Truth about God