Toll autoroutes in France are basically empty most of the time and therefore very easy driving. Of course if you are there around the end of August as everyone in France returns from their month - 6 week summer holidays then all bets are off regarding traffic. The rest of the time the only hold-ups occur around the big cities where the autoroutes become free. This is a great planning site for travel in France https://www.bison-fute.gouv.fr/index,langen.html Go to the calendar and it shows expected traffic conditions as Green, Amber, Red and Black which is pretty self explanatory!
Of the 3 suggested routes from Nice to Annecy I'd take the longest one that heads west towards Marseille and then up past Avignon. The east going one that takes you through Italy can be very busy along the coast to the border and up towards Turin. I don't know the route that heads straight inland from Nice.