Help me select a breed LGD

Hello everyone, i wanted to ask two questions about the coats of different lgd breeds and best lgd for free range chicken farm.
1-Which dog is more heat tolerant? A white double coated long haired breed or a dark coloured double coated medium haired breed? The breeds i am talking about are not so famous outside my country. They are the White greek shepherd dog and the Mollosus of Epirus.
2-Also which independent ((in pair but) without human supervision most of the day) lgd breeds are good for chickens, that are both heat and cold tolerant?
Thank you in advance for your answers.

Welcome to Permies Konstantinos!

I am reading between the lines and assuming that you are from Greece?

I do not have a recommendation, but I do have a question. Have you had experience training dogs before? (Pet or LGD?) I did a little lookup on both dog options that you presented and I'm amazed by their histories. Chickens are the ultimate prey so you will want to make sure your LGD understand that they are friends and not food. I have a pet hunting dog and lucked out that her drive didn't lead her to kill chickens. She just corrals them now for fun. I think she thinks she is herding dog but I don't have the heart to tell her.

In general, thick double coat protects both from heat and cold. But there are other factors, like body fat and mass, etc.

I didn't know about Greek Shepherd dog! It's always cool if you can engage in helping to protect a landrace while giving it a job it was made for.

Yes, i come from Greece.
When i was young my family had a female non pedigree German shepherd.
The white Greek shepherd dog is leaner (with longer coat) than the Mollosus of Epirus, i think.

I've had quite a few of the LGD breeds that are available in the US, but have no experience with the breeds you mentioned.  I suggest you talk to a couple of breeders of each breed (to get different viewpoints), and see what they think.  

As far as training them to leave chickens alone, if you don't have any other dogs around chasing chickens for them to copy, it should be fairly easy to teach the LGD's to leave the birds alone.  Usually around six to eight months old is the danger zone; that's when most of mine have killed a chicken or two and had to be soundly scolded (and spanked, in a couple of cases).  As long as there aren't other dogs on the place chasing chickens, that should be all it takes for most dogs.  

I have a Central Asian Shepherd that I adore.  She lives with my other dogs, 12 cats, 40ish chickens, and gets along well with all of them.  LGDs have near zero prey drive, so you shouldn't have any trouble getting them to accept your chickens as family.

I'm not familiar with the breeds you mentioned.

We have Colorado Mountain dogs, and they've done great with our crazy weather. We run anywhere from 105 to -27, and it's not consistent either (a couple years ago we were 100 one day and had a foot of snow and were sitting below freezing the next). We have quite a few animals, and run them in three different places with three different dog teams. We run them with sheep, goats, cows, alpacas, chickens, ducks, and geese. We only have one trained to effectively guard the poultry, but are planning on starting another one this winter.
I will warn you, the ability to guard chickens comes from 1) The individual dog. Every dog is different, and some dogs are automatically better poultry guardians than others. We have one boy who doesn't seem to care about chickens, and another who chased them with regularity when he was in with them full time. 2) Training. You can do a lot with training to help dogs learn not to chase chickens, however I would highly recommend starting with a dog that's naturally less prone to chasing them.
We did a lot of research when we first got into LGDs, and learned a lot about different breeds. We picked the Colorado Mountain Dogs because of two reasons. Firstly, because most of their guard work is preventative. They start by barking at whatever the threat is, instead of waiting until the threat is immediate and requiring attack. Some guard dogs act first and think later, and others think first and then act later. We deal with coyote pressure, and barking is much more effective at keeping them away than dealing with a pack attacking. The second reason we chose them was because they are much better with people.
Just out of curiosity, why are you looking for an LGD? If you only plan on having ten chickens on half an acre (as an example), you don't need a guardian dog. You need to understand that guard dogs aren't like any other animal (although it sounds like you might have some LGD experience?). They need a job 24/7, and they will go stir crazy if they don't have something to do. Some guard dogs are better at being house type dogs than others, so keep that in consideration when you make decisions about them.
Also a good point to keep in mind, don't expect your guardian to act anything like your German Shepherd. If you get a good LGD, they are bred to think on their own, and aren't easy to train. You can convince them to stay... mostly, and sit, fairly reliably, but don't expect them to be like a herding dog that's lapping out of your palm just to please you. They are independent thinkers and very territorial: that is what makes them good at their job!

Vey good looking dogs!
I didn't know the breed.
Also i thought great Pyrenees are not heat tolerant (read that there is blood of them in your Colorado mountain dogs).
I plan to make a chicken farm for eggs in the future.
Half acre fenced.
So i want a dog that
1-can withstand -13 to +39 celsius.
2-be good with chickens and me.
3-be independent.
I am also considering a small very rare dog breed named Alopekis.
Maybe combine two of them with a big lgd such as the Greek white shepherd.