I am a strong believer in making SA ( Situational Awareness ) one's absolute top priority, and for them to constantly practice their SA technique ( using Good SA habits/practices )
and note..... noone ever "masters" SA ( Situational Awareness )....... SA is a never ending practice of habit.....
then , my next major question would be, why did everyone who has posted so far, not give any consideration to BFM ( also include gunnery skill with this ,too ) , being more important than ACM
in the past, I had always put SA at the top....... then would continously give repeating lil refresher courses on SA, through the stages of teaching aircraft control, and BFM
I consider E-Management a part of SA
hope this helps
<S>
TC / VlPER