One of my ML teams uses 4-3-3 exclusively.
Depending on who I'm playing:
Balance (CMF needs to have great stamina, decent pace and passing, like a Machado, Kaiser, Reo-Coker, DMF needs to be a "destroyer", ie, Bradley, Bianchi, Makelele, Mascherano, etc...):
-----CB----CB-------
RB---------------LB-
---------------------
-----DMF------------
---------------------
-----------CMF------
---------------------
---------------------
------AMF-----------
-----------------LWF
RWF-----------------
---------------------
---------CF----------
___________________
Thermopylae (one pure "destroyer" DMF sitting deep, another both solid defensively and EXCELLENT in passing/playmaking slightly ahead, like Alonso, Pirlo, Aaltonen, etc...):
-----CB----CB-------
RB---------------LB-
---------------------
-----DMF------------
-----------DMF------
---------------------
---------------------
--------AMF---------
---------------------
RWF-------------LWF
---------------------
---------------------
---------CF----------
___________________
That Holding Bastard (you need a scary motherfucker of a DMF to make this one work in Top Player. Someone like a developed Huddlestone, Heitinga, Bos, De Jong, Vanden Borre, who can break up play, pass, create, attack themselves, and still comfortably get the hell back to cover. Your enemies will learn to fear your DMF, because he's damn hard to knock of the ball, his shots from the top of the box readily and routinely break fingers, and he's basically omnipresent. Seriously, I've had some of these cats score 20 a season.)
-----CB----CB-------
RB---------------LB-
---------------------
--------DMF---------
---------------------
---------------------
---------------------
-----AMF------------
------------AMF-----
---------------------
RWF-------------LWF
---------------------
---------CF----------
___________________