I have never been a fan of 3 defender formations.
My favorites are:
451V, if my AML/AMR are good i give them red arrows also if i want to be a little more offensive,
4222 Hexagon, if my defense is really strong and I can afford the extra forward
Narrow Diamond: If my wings aren't great but I have 2 good strikers

I more use the arrows for in game adjustments, but as previously stated, the best formation depends on your opponent and who is playing well on your team at that time.