Real Madrid and Barcelona are inseparable when it comes to Spanish soccer and its global popularity. It's not simply a matter of success – of which they've experienced much over the years – but because they feature the two most dominant and decorated players of their era in Cristiano Ronaldo and Lionel Messi.
As two of the richest clubs in the world, that type of talent will continue to come through their front doors, keeping them at the top of everyone's "favorites" list.