Destiny Littleton is a much different player than any of the four guards. She's a power scorer from the wing, and thanks to Bishop's offensive strategy, she's put up monster numbers. But in club ball, she's not nearly as notable, though obviously she's still a good player.
The comparisons ...
Clarendon: Was a two guard who focused on scoring, as I recall. Nice mid-range game who exceeded expectations by becoming a starting point guard in the WNBA. All credit to her for steadily improving.
Boyd: Closest to Littleton in terms of strength, but a point guard all the way. And of course, she can't shoot. Littleton is much more versatile offensively.
Thomas: Really no comparison, as Thomas is small and slight, and a point guard. Thomas was also coming off an ACL.
Cayton: Cayton isn't in Littleton's class as a scorer, and is more athletic (though not as strong). With scoring ability at such a premium in the women's game (no one can shoot, really), Littleton is more highly prized.
Now, all this said, I didn't see a lot of Clarendon at the high school level, and I haven't seen that much of Littleton.