4-2-3-1 is another balanced option:
.................De gea................
Rafael...Rio..........Vidic...Evra
............Cleverley....Carrick.....
Valencia.....Rooney.......Nani
....................RVP..................
Obviously personnel can be changed but I think that formation gives sufficient attention to both attack and defence. Another one to try is a 4-3-3:
.................De gea................
Rafael...Rio..........Vidic...Evra
Valencia...Carrick......Cleverley...
Nani...........RVP.......Rooney
This is referring back to the Ronaldo-Tevez-Rooney partnership where all the forwards were fluid and could exchange positions at ease. Again personnel can be altered and several different combinations can be played.