I have been line breeding Cream Legbars for 7 years and the egg color in my flock is just start to get really consistent. We have friends two doors down from us who have Ameraucana. We tend their animals when they are out of town and currently have two dozen eggs from their flock on the counter in our kitchen. With the side by side comparison our Cream Legbar eggs are hands down better colored (and larger, better shaped, and better shell texture). They get 5-6 different shades of egg color that range from a dull grey color to varying shades of green. They get a few that are fairly blue but they are a pale faded blue. Our Legbars all lay a light blue color egg that is uniform across all the eggs from the flock and a far more saturated blue than the Ameraucana that our friends have.
The trick to egg color is NOT the breed. The Legbar, Ameraucana, Aucana, Easter Eggers, Maidenrock Bantams, etc, etc, etc all get the blue egg coloring from the same gene. They also get egg color genes from about 20 other genes that change the
1) texture which can effect how the color shows up,
2) that can produce cream, tint, tan, blown coloring in the shell that mixed with the blue pigment effect the color,
3) That can produce coating on the surface of the shell that can cover the blue base color or mix with them etc.
The Blue coloring is straight forward. You either have it or you don't. The 20+ other genes is what gets tricky. Since they are all passed differently (i.e. some dominant, some recessive, some have linkage to other genes, etc.) it can take decades of culling to get your flock to consistently product the perfect egg color. Some Ameraucana breeders have been type breeding for egg color for decades. If you get stock from them the egg color will be really good. Others mix lines or even breeds to increase egg production or to created new color patterns in the plumage, or to create sex-links, etc. Anytime a line is crossed you bring a lot of variation onto the mix and egg color and other traits can be unpredictable and traits have to be re-established. If you get stock from a mixed line then you will likely get something more like what our friends get. A large range of colors with none of them as impressive as a line breed blue egg layer.
Have you asked to see eggs from the Ameraucana and Legbars? She what color the breeder is getting in their line before you take a risk on the unsex Ameraucana.