#3 Hendon Hooker, #2 CJ Stroud
The QB S2 COG Test was not kind to either of them.
Does the QB S2 COG Test matter? To me, it matters a lot. To scouts and GMs, it matters a lot. However, I don't think coaches care as much (if they care at all). In my experience, coaches don't want "know-it-alls" behind center. This got me in trouble in my collegiate career. Whether I was right or not, I was confident in my decision making and my ability to change plays. Even when I was right, this caused friction. NFL coaches are much more arrogant than college coaches (usually). The value of this test will vary greatly from organization to organization. Jameis Winston was terrible at aptitude tests, yet he was the #1 overall pick in 2015 because of his physical abilities. Say what you want about ol' crab legs, he threw a lot of touchdowns.
I'd be lying if I said I wasn't shocked about Hendon Hooker's score on the QB S2 Cog Test. He was an excellent student at Tennessee and has been a masterful student of the game. His improvement through his college career is rivaled by few. I mean, he only through 5 interceptions through the last two seasons COMBINED. Stroud is no slouch either. I don't think the results of these tests accurately reflect the mental potential of these two quarterbacks. However, I do believe that Bryce Young's score proves that he belongs at the top of this class.
Here are the scores for that test, according to The Sporting News who posted a phenomenal article explaining the test (highly recommend you click that link and read that article).
Tanner McKee -99th percentile
Bryce Young -98th percentile
Jake Haener -96th percentile
Will Levis -93rd percentile
Jaren Hall -93rd percentile
Clayton Tune -84th percentile
Anthony Richardson -79th percentile
Hendon Hooker -46th percentile
CJ Stroud -18th percentile
By clicking on any of those links, you can see where I ranked those quarterbacks in previous articles. Like I said, if I was a scout, I would value this test a lot. But I know many do not care about this. That score has nothing to do with skillset, which is what gets you drafted. If there are deficiencies in recognition or speed of decision making, we haven't seen them in Hendon Hooker's play the last two seasons. We didn't see them on the biggest stage of CJ Stroud's life against Georgia.
While I do care a lot about this test, it does not change my rankings.

#3 Hendon Hooker