Rosen is the best prospect. I think that's pretty obvious, imo. Watching him and Darnold...yeah. Darnold makes some great plays but he's a turnover machine. Not to mention that he's super, super green and really hasn't learned to go through progressions (when I watched him anyway).
Rosen, to me, seems like the kind of quarterback that the braintrust wants: big, pure passer, goes through reads, makes good decisions, and smart. Seasoned.
I would trade up for him. I think that's their plan as well, but we shall see!