I still don't want to draft a QB, but if we do it comes down to whether you'd prefer the intangibles or the skills, as Chaz said earlier. I don't want the projection - draft a quarterback with at least ONE of those two things maxxed out already from a draft-pick prospective, please. Both Oz and Lynch were "projectible" but failed at both the skills challenge and the intangibles one.
So if you want skills, I probably go with Rosen. His arm is terrific and accurate, he can read defenses (not that the Pac-12 is stacked with NFL-caliber defenses, but he can read them and react quickly through his progressions) and he's mobile enough. He might be made of glass, I dunno, but I'm not worried about his ability to from Option 1 to Option 2 in his reads without TILTing out to checkdown and pissing himself 85% of the time. He makes dumb, overly-aggressive throws under pressure but so do a lot of talented kids.
If you want intangibles (on a football field, not after a game or while drinking I guess) I go with Mayfield. He wants to compete and win more than most people want anything in their lives and his teammates make blow up dolls of him for home use. Unlike Brock and Paxton, again, he can inspire the troops and embraces challenge. I'd like to challenge him to leave his balls alone in his work pants for a few hours, but be that as it may I agree with Chaz: if he was three inches taller he would be the no-brainer #1 QB despite attitude concerns.
And Rosen has attitude concerns too. I'm fine with that. Brady is a dick, Manning mooned women in the locker room and is also a dick, Rodgers is a cocky jerk... if we can keep on this side of the Big Ben rapey line that would be great. This team could use some swagger. You'd think of all the things Elway looks for, being unafraid of the moment and having some sass in your step would be something to check.
If we draft a QB we have to figure out how to keep them upright, which is why I'd rather do that first. But if the Broncos are going QB with their top-10 pick, then grab somebody who's actually good at something please. A QB is not a horse - I don't care about his withers and how many hands tall he is. Get someone who can do at least one part of his real job, and then teach him to do the other one.