Its a group 4 badge
Air Assault is group 4 as well (which I have).
When I was at Fort Campbell, many leaders told their Soldiers who had jump wings, that they better wear that badge below the air assault badge and when that Soldier went to the 82nd or 173rd, they were "ordered" to reverse those badges.
Point is, it does not matter which badge goes on top but if you look at the above link, the parachutist badge should be on top. But personally, I think there will be no problem on which one you wear on top.
But I have see three stackers who have wore their pathfinder badge on top, then airborne, and air assault afterwards. It appears to be aesthetically better.
But read about precedence here
and page 246 http://www.apd.army.mil/pdffiles/p670_1.pdf
shows airborne badge on top of mff.