From the selection powerpoint:
"Per USAACE policy, active duty officers and warrant officers select their advanced airframe based on the cumulative grades earned during the courses leading up to the completion of Common Core. USAACE G3 determines airframe MDS distributions.
Compo 2/3 students are assigned aircraft by their owning state.
MSC Students only fly HH-60s." (Aka 67J's)
So active duty competes against each other O vs O/WO Vs WO but not O vs WO. NG/USAR/67J all should already know their advanced airframes and not really a factor, but kinda a factor. BN gets the stats for projected Army needs a day ahead or so and then everyone (active duty) is racked and stacked based on OML which the breakdown of that can be found on teams also.
This is my best interpretation of everything I've seen and told from people in the pit.