I like the silenced MP 9 my self, since I don't always use a silencer on my main weapon.

The FMG9 is the best secondary, just run it akimbo. The ONLY class that your FMG's wont be the better choice on is a shotgun class simply because of the ranged effectiveness of the MP9 helping to round out the class. On every other class you have a long range option and the FMG's can handle medium close easy as hell.

BUT FOR THE LOVE OF GOD STOP F*CKING USING THEM! Don't just pick which ever stuff is strongest or you classes are all only going to have ACR, MP7, FMG akimbo. Use other things, and for christ sake, for every one and your self, don't use the FMG akimbo. Every time you do God clubs a baby kitten or polar bear to death.

it depends what r u using it for besides secondary do u want a assault, automatic,or pistol???  me i choose mp9 silenced

FMGS are by far the best option cqb, hands down best secodary. They also basically switch as fast a pistols after the first switch, kind of retarded and the main reason they are on most my classes next to their insane fire rate.