i have 4 Teams. 3 Teams Play 4-4-2 C and 1 Team Play 4-3-3.
my 4-4-2 Teams are hard to beat.
Lvl 6 4-4-2 1. place in league, 1. cl Group, 1/8 in Cup Players: 3x 4*, 4x 5*, 4x 6*
lvl 9 4-4-2 5. place in league, 1. cl Group, end in 2. round in Cup Players: 7x 4*, 4x 5*
lvl 25 4-3-3 3. place in league, 4. cl Group (opponents are 2 lvl higher), 1/8 in Cup Players: 1x 3*, 5x 4*, 5x 5*

I don`t follows the games of this accounts.
Best results are with 4-4-2 normal, mixed, own half, short, hart. no arrows. it´s hard to beat.

4-4-2 is the most balanced Formation and will help u most of times. But if u are a good Manager, u will beat every Formation with 4-4-2.
But with 5 or 6 Players in the middlefield you can get more controle in the match. (4-2-3-1, 4-5-1 v, 4-3-2w-1, Butterfly)
But Keep in mind, only the right orders can make a Formation strong and every time you have to find out the right orders when u follow your game