What would God prefer: to hear praise songs flowing to Him or see justice & righteousness flowing to others?

Great question! God of course wants us to live by His example and share His love, and righteousness. We must be careful when administering justice, as the world knows justice, for we are a fallen people and what is justice to one, may not be so to another. I would never change or try to change Gods Word, but I think that justice here should be interpreted as love. Jesus set that example before us with the woman caught in adultery, and the Pharisees demanded justice, to see what He would do. None of us would want justice given to us for our sins but, yet pray for mercy and love. If we all received justice for our sins we could not stand under the weight of it. God loves our praise and we praise Him for the sacrifice He has made for us, taking our sins so that we may be justified in faith, by grace through Christ. When we praise Him, I think we should take a page from King David and do so with all our heart, and if we truly know and repent of our sins we do, because we understand the justification that has been made by Christ for us. This is the justice that God is speaking of here, love. And yes, He would rather have us love one another, and Him. Then all the praise in the world. Fore He can have even the rocks praise Him if He so desired.