Jackson's shot form looks broken, even in that youtube vid of him practicing on fixing it. He is dynamic other than that but like others have said, this league has seen so many players come in young with horrid shots that are never able to fix it.
If he had good form, say like Avery Bradley, coming out of college, then I would think he would be on the same level as Fultz. Bradley's shot eventually came around because is form was excellent. Not sure Jackson's ever will.
Fultz, OTOH, has a smooth as silk shot, excellent stop and go, elite coordination and control, and excels at all three areas of offense, 3-point shooting, mid-range game and ability to finish. And I can see where a defense first kind of coach like Stevens will get Fultz to eventually plat grest defense.
Don't overthink it too much, Danny. Just draft Fultz.