I put my money on Sam Darnold of Southern Cal. You remember Tee Martin, don't you? The QB that led Tennessee to their second National Championship has advanced his career to Offensive Coordinator at USC. An interviewer asked who was better Tee Martin or Sam Darnold. Tee laughed and admitted as a freshman Darnold was much better a quarterback than he was as a junior or senior at Tennessee. Asked what famous quarterback he resembled Martin thought for a few seconds before remarkably comparing Darnold to Aaron Rodgers.
After reading that article and a few others I decided to watch the Rose Bowl on youtube pitting 8-3 Southern Cal verses 9-2 Penn State. What I witnessed was awe inspiring. Darnold has more velocity than Andrew Luck with possibly more accuracy. You remember how Peyton had "Happy Feet"? This dude can best be described as dancing in the pocket with a mobility that doesn't resemble any quarterback I can remember especially for a big 6'4" 230 pound quarterback. But the most striking attribute Sam Darnold displays is his cool hand Brady like composure in the pocket or when forced to scramble from an extreme rush.
In the 2017 NFL Combine the gurus talked more about Darnold than all the leading quarterbacks ready to enter the draft. Is this kid a Andrew Luck 2.0?