Dude, long story short, you can rate Modric however you want. Most knowledgeable fans will rate Xavi and Iniesta a tier above him without hesitation. If you believe differently... well... watch some more games of Xavi and Iniesta. 5-0 vs Madrid will be a good place to start and see what a midfield masterclass is.
Never seen godly performances like that from Modric where he completely toys with the elite sides of the world. In some ways I actually expected Madrid with peak Modric and Kroos to really smash us, but even older Iniesta and Busquets, with prime Rakitic added, were at least even quality with Modric and Kroos.
Imagine what peak Xavi and Iniesta would do to them. There's world-class, and there's beyond that. Modric, Kroos, Busquets, belonged in the world-class sector. Xavi and Iniesta went beyond that.
They are to midfielders what likes of Pele, Romario, Ronaldo Nazario are to strikers. Best of the best.