"highly favoured" is a very bad translation of "kecharitomene", -- full of grace.
"Grace" appears in Luke 2:40, John 1:14, John 1:16, John 1:17 in the Gospels; each time the Greek original is "charis". What warranted the tortured "favoured" in Luke 1:28 of NIV we can only guess.
Actually the ONLY place it is translated as full of grace is in the Alexandrian text.
But I do say ask who gets the praise the giver of the gift or the recipient?
It is God that chose Mary as the human mother of Christ and it was God that prepared her for that role. She was nothing in herself without Gods grace. All the praise goes to God !