Mediterranean breeds are better layers but not as cold hardy as other breeds. There are hybrids like sex links that are excellent layers too and cold hardy. If your in a colder climate and want a heritage breed then dual purpose breeds that lay well are for you. Choose the type of bird to suit your climate.
There are many variables to choosing a chicken and usually the most important is not function (eggs and meat quality) rather what the bird looks like. Color patterns (variety) of a breed is high on the list so go ahead and choose that then narrow down your choices to Mediterranean or American or other class of chicken. Then choose one that lays the best of what's left. Color of egg may be of importance to you too. Marans, Welsummer and Pendesca are dark brown (chocolate color) layers. Auraucana, Ameraucana and Cream Legbar are Blue egg layers.
If I was in a warmer climate I'd likely have Brown Leghorns or Blue Andalusions (Mediterranean Class). When we first started out we simply purchased chicks form the local feed store in spring. Sex links (both red and black), hatchery production reds and hatchery Barred Rocks are what we got. We were completely inundated with eggs. Being all hatchery stock (they breed for egg production not heritage quality) and traditionally above average layers our birds laid for up to 9 days straight, took a day off then another 8 or 9 days straight. So keep in mind if your not getting a heritage bird from breeder then most of the birds you get from hatcheries will be excellent layers if they are good layer breeds to begin with.