Hello and Welcome To BYC! X4 With heavy breeds you are better off with lower roost bars to reduce the chance of leg injuries. The most popular blue/green egg layer is the Easter Egger sold by pretty much all of the major hatcheries, it is a mixed breed ...many hatcheries sell them as Ameraucana however, which is actually a true breed mostly available from breeders or some small hatcheries. Cream Legbars are another blue egg layer that is getting popular, breeders and some hatcheries do sell them. There are some other more uncommon blue/green egg layers also Araucana, Manx Rumpies, Isbars etc.