Aerospace engineering is one of the most difficult majors at the academy. There is a small boost to Aviation Order of Merit, but it is definitely not worth it to deal with such a difficult major solely for that purpose.
The two greatest roadblocks to aviation are medical and the ASTB. Some people don't have the vision, the reach, sitting height, or whatever. Some people struggle on the spatial recognition and performance sections of the ASTB. Injuries sustained at the Academy have also kept folks from selecting aviation.
You can study for the ASTB, and you definitely should not underestimate it. Not much can be done about medical if it's not something PRK can fix.
There's a push to make powered flight a requirement for aviation selection like Leatherneck is for Marines. It's not quite there, but pilot hopefuls are strongly encouraged to take powered flight. And while your grades and standing may be excellent, the nuke community comes in once in a while and wants to hold a Service Assignment Review Board; the aviation community is more likely to fight for the people who have done powered flight and 1/C aviation cruise and proved themselves worth fighting for with demonstrated potential and commitment to the community.
If you want NFO, they were putting SWO selects through SARBs to go NFO last year and have been for the past three years. Needs of the Navy may be in your favor there.