@Nils there is no best formation and you aren't only one who has a lot of trophys.
@Besss I would suggest normal mentality, mixed passing through middle, zonal marking, blue arrows on 2 ST and on one MC.
You don't need to add red arrows because 43n3 is attacking formation by default. Adding red arrows will expose your defence too much and make your team vulnerable on counter attacks + your ST can run in offside too much. You won't see that in statistics because there aren't offside stats. You can notice it as low number of attacks and shoots. Be careful against strong wings formations and against teams who play defending with offside trap. I'm playing with 1ST formations and without or only few arrows; at this time i'm leader in league and waiting for 2nd CL leg after 3-0 win. I'd suggest to use red arrows only when your team is down with result and you have to score asap.