Black copper marans from a known line of very dark eggs over crested cream legbar hens.
To get true olive color you need the marans to be from a breeder that breeds for egg color otherwise you'll be producing green instead of olive green eggers.
I also like CCL rather then ameraucanas because they lay better and the cross produces sex linked chicks so you can guarantee pullets when selling.
I did the opposite, so mine aren't sex-linked

I have one black copper marans hen with my flock of cream legbars. I liked the CL rooster better than the BCM rooster.