In my opinion, the best antiphon beside the O Antiphons (which begin tomorrow at Vespers), and I am merely echoing the informed opinions of liturgical scholars, is the Rorate caeli (Rain down you heavens) antiphon in the Advent season. It is the expectation of Israel seen through the eyes of the prophet Isaiah (45:8). The whole purpose of the Incarnation is spoken of here:

Drop down dew, ye heavens, from above, and let the clouds rain the Just One.

Be not angry, O Lord, and remember no longer our iniquity: behold the city of Thy sanctuary is become a desert, Sion is made a desert. Jerusalem is desolate, the house of our holiness and of Thy glory, where our fathers praised Thee.

Drop down dew, ye heavens, from above, and let the clouds rain the Just One.

We have sinned, and we are as one unclean, and we have all fallen as a leaf; and our iniquities, like the wind, have taken us away thou hast hid Thy face from us, and hast crushed us by the hand of our iniquity

Drop down dew, ye heavens, from above, and let the clouds rain the Just One.

See, O Lord, the affliction of Thy people, and send him whom thou hast promised to send. Send forth the Lamb, the ruler of the earth, from the rock of the desert to the mount of the daughter of Sion, that he himself may take off the yoke of our captivity.

Drop down dew, ye heavens, from above, and let the clouds rain the Just One.

Be comforted, be comforted, my people; thy salvation shall speedily come. Why wilt thou waste away in sadness? why hath sorrow seized thee? I will save thee; fear not: for I am the Lord thy God, the Holy One of Israel, thy Redeemer.

Drop down dew, ye heavens, from above, and let the clouds rain the Just One.