451v work best for my team. actually its not the formation but more on tactics but sometime luck plays a part. if the system want you to lose nothing you can do. i lost my first league game this season using a 442classic v 451v 0-3. So i switch to 451v never change my formation regardless any formation i played against, so far unbeaten.
Base on my own experience not much abt formation but tactic , player and luck. that how i feel.