Nice one. I'll keep it to Brittany/Breizh/Bretagne only since some people might have other things to say about France. I also just will tell few coming through my mind:
1) According to legends, Brittany has been created by 7 Saints. These founders came from Britain (when Anglosaxons invaded the place) and were monks and hermits Welsh or Cornish for most. The existence of the country is prior to France and many other european existence.
2 ) In Brittany was written the Catholicon, which was the world first trilingual dictionnary and book, but also the first Breton dictionnary and the first French dictionnary at a time in which Brittany was an independent Duchy (the third language was latin).
3 ) The first stethoscope was invented by a Breton because his patient, a woman, was difficult to auscultate.
4 ) Brittany is geologically different from the rest of France. Its territory has rocks from the hercynian era and older, and the remains of the Armorican massif was at least as high as the Alps, but has been wiper by the oceanic climate. It's also one of the three places in the world where you could see a pink granite coast.
5) Brittany has a central position in maritime european rouotes (right between Spain, England, NEtherlands), hence it was an important area for the world commerce during the XIV-XVth century. Due to that, major power in EUrope always have wanted to get a hand over Brittany which has led to plethora of conflicts in the area.
6 ) Brittany has long been the bread basket for Europe. The whole production but buckwheat used to be sold in its totality in the past, and still a major part of the breton production is exported out of Brittany.
7 ) The climate in Brittany is extremely mild thanks to the oceanic climate. Indeed, expecially close to the coast, it's rare to experiment either cold or hot temperature and it's usually spared by the hotwaves or the coldwaves.
8 ) Although it's a small place comapred to others, Brittany is culturally diverse and different customs has emerged depending on where people live. It also has three languages; Breton, a celtic language close to Welsh, Gallo, a romance language and French. Breton was formerly divided in various dialects that have been unified ina standard Breton in order for it not to completely disappear because of former policies.
9 ) There are plethora of archeological treasures among which you could find the oldest building of Europe and the second largest megalithic mausoleum of Europe, thousands of menhirs and dolmens, roman ruins,
10 ) There is a 130t stone that you can move with a single finger in Huelgoat's forest. Talking about forest, Broceliand forest (arthurian legends) is also believed to be in Brittany, and you could find Merlin's grave there.
Well, it's messy and there are other things to say, but it's good enough.