The Necessity of God Creating the Universe

I think there's a certain necessity that God would create the universe which he most desires. I don't think it necessitates metaphysically, but it does raise the question as to why would God? St. Thomas uses the word belay to us desire for God. So I think there's some orthodox backing for using the word desire with God. But why would God desire one universe as being most fitting for accomplishing precisely the end that he has in mind for the universe and not choose precisely that universe? That to me is the real question there.