I think Christian McCaffrey is the best player in college football right now. He is to dual threat RBs what Mike Trout is to outfielders. He can do it all, and do it all at an elite level. He can take over games, with or without much help. I'm guessing he'll go middle of the 1st and be a huge steal for some team.
Watson is a bit like Mariota, he's so smooth and talented, it's almost boring. That said, at his current weight (210 pounds) he had better run a RG3 / Mariota type 40 time. Otherwise I could see him slipping a bit since teams only like super fast or super bulky mobile QBs in the top 10 picks.
If Royce Freeman had been in the 2016 draft, I would have been just fine with Seattle spending a 1st on him. You won't often find battering ram RBs with better talent.