Never mind just Xavi and Iniesta, it's the understanding of the entire forwardline of Xavi, Iniesta, Pedro, Messi and Villa that makes them incomparable with any other attacking line-up in the world. To compare Xavi and Iniesta as individuals to other guys like Silva and Fabregas is very difficult becaus essentially they are of the same mould, ie classy playmakers, an eye for a pass that only special players possess and the ability to make their lack of physical stature count for nothing as they control games with just sheer footballing brain power.
It has to say something for Xavi and Iniesta that they are arguably the first names on Spain's team sheet, keeping Silva and Fabregas out of the side along with other similarly fantastic talents like Mata.
A different debate would be to compare Casillas and Valdes. Both of them are outstanding most of the time but they can both drop the odd bollock here or there, yet every time it's Casillas in goal for Spain, in fact is he not captain? You could easily argue a case for Valdes being Spain's number 1, behind a Puyol and Pique.
It's fun to compare these great players but even more fun to watch them at the peak of their powers as they are now. It's about time Spain started to flourish and I can't think of a nation more deserving of being World and European champions.