Between Ameraucanas, Cream Legbars or Whiting True blue, which lay the bluest eggs?
It's going to depend on the individual chicken. There is one gene pair that determines if the eggs are going to be base white or base blue, that is fairly easy. But there are many gene pairs that determine the shade of the egg.
There are all kinds of breeders in the world, breeding for their own purposes. If they know what they are doing and they carefully select for blue eggs they can get a really consistent blue egg layer. Even the breeders that know what they are doing may not put that high an importance on specific egg color/shade. They may be more interested in feather color/pattern, body size or conformation, comb type, or egg production for example.
Many chickens sold as Ameraucana really are not. They are basically EE's sold as Ameraucanas. If you can get a good one you can get a really good one but you need to know what colors of eggs the parent flock lays. That's not always easy.
The UK SOP for Cream Legbar allow blue or green eggs. Last I heard the American Poultry Association has not approved the Cream Legbar but the group trying to get them approved has applied for both blue and green eggs to be acceptable.
You can read the customer comments on the Whiting at McMurray's website.
If you can determine what color of egg the rooster's mother and both grandmothers laid you can get a pretty good idea what color genetics he will bring. But that is based on individuals, not necessarily a breed thing.
Sorry, this is probably not much help to you. Do the best you can but don't depend on breed. There is more involved.
