I don't think it would be appropriate for one to place one league above the others, especially the four main European Leagues such as Spanish la liga, English premiere league (EPL), Italian siera A and German bundles liga. Honestly, these various leagues have their peculiar philosophies and style which immensely influence the leagues structures. And these structures are the intrinsic determinants of the popularity and level of competitiveness in these leagues.
However, there might be strong arguments that one of these four league is better than the others, perhaps due to its level of competition, popularity, financial muscle, or calibre of players in the league. Majority of people use these parameters to judge which particular league have the edge over the others. No doubt, when it comes to popularity, financial muscles and competitiveness, EPL have the edge in these areas, but that does not make them the best, because there are key things that other leagues have that they don't have.
For instance, La liga have the fluidity in terms of play, siera A have defensive pedigree while bundles liga have fluidity and great mental strength.
Looking at all these criteria, you would notice that they is no particular league that have them all. For that reason, it won't be right to say one is better than the others.