David Johnson, I think. Would really love to trade out of that pick though. If you don't want to go RB, I have no problem with Amari Cooper either. I would also have Howard or Ajayi nowhere near my top ten in a Superflex dynasty.
I play a good amount of Superflex, and it's very intriguing because people don't know how to evaluate the QBs. Everyone does it differently. Even the "experts" on sites have some pretty terrible Superflex or 2QB rankings, though even saying that it's just my subjective opinion saying they are terrible.
That said, I would draft QBs extremely high. The teams that have two good starting QB's are consistently the top ones in Superflex leagues. The group that I would target is Winston, Mariota, and Carr and try to pick one or both the 2nd and 3rd round.
If you do get DJ, you could also just become a win-now team. Draft Brady & Brees in the first 5 rounds and you will be in the championship mix immediately with those three. Just depends what you are trying to do.