The Great Company as spirit beings will be higher than the Ancient Worthies Millennially. But after the Little Season, when the Ancient Worthies become spiritual, the Great Company, the antitypical Merarites, will have the highest place under the Ancient Worthies—the antitypical Kohathites—and the Little Flock-the antitypical Priests. The reward of the Great Company is a glorious one indeed. (For details on this class, see PT Nos. 562, 563.)
"Those Consecrating Between the Ages" (Z 5761) seem to be referred to by the "small" in v. 18. Like the Ancient Worthies, they have received the enlightenment, heart-warming and energizing of the holy Spirit, but not the Spirit-begettal. As earthly seed of Abraham, they will be associated Millennially with the Ancient Worthies in the blessing of all the families of the earth.
The Youthful Worthy class (literally youthfuls, Joel 2: 28) among them consists of those who consecrated from the Fall of 1881 to the Fall of 1914 and remained loyal, for whom no crowns were available and all those who consecrated from the Fall of 1914 to the Fall of 1954 and have remained loyal.