I would go with a young veteran QB. The two names that I think would be a good fit are:
1. Jameis Winston: If he could reduce the turnovers, he would be a great addition to the offense.
2. Mitch Trubisky: Granted, he's not Mahomes or Watson but he's not a total bust either. I think Trubisky could blossom with a change of scenery, like Ryan Tannehill.
Also, since both Winston and Trubisky are free agents, you don't have to trade any draft choices.