I would say Easter Egger on this one. A few of mine look like this. But I'm still new to chicks, so again, I could be wrong. I'm very interested to see what your little grey one turns out to look like. Please post updated pics as she/he grows.
I have two black/brown and one that looks like this that are all supposed to be Ameracauna/Aracauna EEs But my two Welsummers look similar to this, they have more red than the other.