when are you thinking of travelling?? I ask as if it is shortly then the route I use would be different, ie, I always use the Somport tunnel, Pau is my last stop in France, at this time of year all the routes through the Pyrenees ie, the tunnels could be closed due to snow.
Have a look at the "about France.com" website
Lots of useful information about France and Spain and the respective routes through France to Spain,
Basa
There are several best routes depending on your criteria. Some may become affected by snow at this time of year. First question. Do you want the easiest route regardless of toll costs? This route will be motorway from Calais to Benidorm. Most of it toll cost around £140 one way for motorhome.
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.