I'm joining in this discussion because I ,too, am interested in spending months away during the Winter- though I'd probably go and back and forwards to ireland ,so cheap flight availability is important-which rules out Greece,Cyprus, Turkey.
Reading the above posts and having lived 15 years in Europe, mainly the Med,especially Greece I'm torn between renting in c.del Sol and Fr Riviera. Each place has pros and cons...
I can get by in a few languages (boast boast. mind you, never managed Irish as never found anyone who speaks better Irish than English) . If I didnt know the language I'd be reuctant to live long in a country. I'm too old to learn another one.
Knowing the language enhances the enjoyment of a long stay anywhere.
So,OP, if you're fluent in french that must be very important .
Nice can be much cooler and wetter than Malaga in Winter.
On some days it's as cool and wet in Nice as Dublin. Actually, Dublin's milder than most of Europe i Winter -and that includes the interior of some of Med countries. Twenty miles behind the coast in the Med up in the hills can be very chilly in Winter .
So, for weather it's Malaga area -and apartment rentals are nearly half the price of Nice.
But then ,Nice is so close by train and car to so many more places than rather stuck-out Malaga. Malaga does have great cities nearby but for choice and variety of places to visit Nice is a great base. If you want to explore Southern France ,northern Italy, switzerland then you're only a few hours away.
So,because of your knowledge of French and interesting exploring it must be Nice for OP.
But because of better weather and much cheaper accommodation it must be Malaga.
Whatever you do don't spend the Winter in some "quaint" village up in the hills of Provence,Andalucia, Tuscany or Crete. They can be miserable, cold dead holes in the depths of Winter. Stay close to cities unless you're going to much warmer Canaries.
Finally, having mulled over Malaga and Nice, Browtall's winter nest in the warmer Canaries is looking more appealing than I'd imagined !!,