North Mediterranean area, Catalonia or French Riviera. France is one of the best natural defense (alps) countries with the atomic bomb. Spain is self defended by the sea. You have The Pyrenees and The Alps as barriers. Access to water, rivers.
On one hand, if Catalans are independent they will be isolated (no EU members thanks to Spain's, and maybe France's veto).
On the other hand, if Catalans are not independent, there will be protests about this, criminality, and maybe even terrorism.
If you like Spain, I would vouch for Galicia (if you like cold climate with rain) or Malaga (international city with mild climate all year).
In 2050, there may be a Northern Hemisphere Jet Stream collapse. Everyone here is posting about how things are gonna warm up - Western Europe is going to cool down probably in a 1C or 2C warming scenario. W. Europe is further north than people think.
The Med is a great heat sink / battery and regulates the local climate. Imagine Nice in the spring, or Barcelona.