Kaka, Iniesta, Fabregas, Xabi Alonso, Gerrard, Pirlo, Rino, De Rossi, Ballack, Lucho Gonzalez, Viera, Mikael Essien will all beg to differ.
I don't want to analyse the playing style of the players that you've just mentioned but I'll try briefly. By the way, I don't mean that he is the best but I mean
more that his style will suit us in this period very much.
1) Kaka and Pirlo don't do much efforts in defending.
2) Xabi Alonso don't play directly behind the strikers besides being slow, he is a great shooter and passer as well though.
3) Gerrard's defending role isn't clear, Lampard is tougher.
4) De Rossi is the best Italian talent during year 2006. Even though, we can't depend on him as a center midfielder, his creativity is low besides being slow as well. I prefer him to be a defensive midfielder though,
5) Vieira is past his best and he can't suit us now, simply, because he is one of the traitors.
6) Ballack is a bug in Chelsea's midfield now.
7) The only one that I prefer to Lampard is the dark beast aka Essien. He is the best defensive midfielder in Europe alongside Gattuso, in my opinion. What is more , he is drastically quick without the ball, he attacks well and I'm pretty sure that he can play role on pitch except being a keeper.
Ballack is not playing well. Pilro is kind of okay at the moment, though nothing like his old performances. all of those players are good, but the most that stand out right now are Fabregas, Iniesta and Essien (I Would also add Paul Scholes). Kaka Is not really a CM so he does not belong on that list.
I wish we could get Fabregas
I do prefer Fabregas as well. However, he isn't that fighter and he lacks the experience that we do need urgently in our midfield.