If all you want is eggs, nothing beats the white leghorn. 300 eggs (25 dozen) per year per bird for the first year of laying. They lay a large white shelled egg, produced by an active and alert hen who can forage for herself and yet she eats the food you buy her like... well like she's a bird.
However, if you intend to hatch any white leghorn eggs you will need an incubator or else some other breed of hen to hover the eggs. All broodiness has been bred out of the white leghorn hen, that is one reason why they lay so many eggs.