The competition between Real Madrid and Barcelona already happens for many years. These teams are too superior in La Liga, only Atletico Madrid that can compete with them sometimes. But in the last 2 seasons, Atletico lost their power because some of the main players move to other clubs. For this season, I agree that one again we will see the competition between Real Madrid and Barcelona for the title race. Although there is Girona in the 3rd place, I don't think they will survive a long time in the top 3. Girona performance isn't very convincing when they played against top teams. It is proven that they got losses at home when they played against Real Madrid in the previous matchday.
We know how competitive La Liga is and only the strong survived. Real Madrid and Barcelona remained the only rivals for La Liga titles every single season over the past decades, often Atletico Madrid enter the race but they don't possess the kind of energy required to lift the title, not consistent and settled for lesser results. More reason I favour and fancy Real Madrid and Barcelona, always in for excellent results. Real Madrid sits top of the table, Barcelona ranked second and Girona demoted to third position after been humiliate by Los Blancos in their last game.
Real Madrid and Barcelona have been in a rivalry for many years. As you said, even if there were years when Atletico Madrid was included in the race, we were usually watching a championship race between the two. I must say that the times I enjoyed the most for myself were the times between Messi and Ronaldo. I think this season will be enjoyable as well, apart from the previous seasons.