my favorite formations are:
4-4-2
4-1-4-1 v

when i was in level 1/2, this is my formation: 3-1-4-2 v. i changed it to 4 defenders when i lost in cl because one of dc got red carded. this caused my formation to be illegal which resulted in losing possession. this formation is still good if you are watching the game. in the cl match, i was not unfortunately.