I don't know how to credit Burrow without knowing exactly what Brady was doing at LSU. It seemed like Burrow knew 100% where his 3 progressions were on every play, so well that that part of the game wasn't an issue. He has the accuracy to put the ball where he wanted, but that first point helps with accuracy. It's easier to be accurate if you know where the ball should go before the snap.
We don't know how much of that was Burrow being a big studier, how much was ease of use in the play-calling/design, and how much was Burrow's on-field talent.
Burrow was athletic enough the 2-3 times per game when none of his reads were there, to escape and gain positive yardage. Tua seems really resistant to cut-and-run, to his physical detriment.
As far as pure throwing, I'd pick Tua.
But he also had a big talent advantage of those around him in nearly every game. Look at his WRs - one has been called "the best route-runner EVER", another runs a 4.2, and the other 2 are like preseason All-Americans. Plus the injuries, plural.
I'm glad I'm not an NFL GM. The percentage of your job that is out of your control has to be inconceivable.