Leghorns are the number one layer. They can be flighty and nervous, but I've found working closely with flighty breeds as chicks lessens this. Many listed as heritage breeds aren't necessarily so. Lots of New Hampshires have Rhode Island red, Barred Rocks have Dominique, Dorkings with Leghorns, etc. Much depends on the honesty of the breeder.
Michael, is that a California Gray in your avatar picture? If so, how are the California Grays?
That is a breed I think should be recognized by the APA.