I know that one of these is a Barred Rock and one is a Black Australorp, the third is probably my Meyer Hatchery Meal Maker (aka random chick male or female). Of course I can just wait and see, but I like the idea of trying to figure it out and see if we are right! The one on the right (C) has no head spot, so I was thinking she is the Australorp and the other two are Barred Rocks, but then all three have eye markings.
Here you can see that the spot coloration is different, A is definitely more yellow (and larger) than B.
The one with the whiter spot (B), on the far left in the photo, also has a more distinctive comb than the other two.
For reference these guys were supposed to have been hatched on January 7th.