First he has to get qualified. From his video, his throwing mechanics and accuracy are ahead of Green, LTW and Martinez already. I'd put him and Spano neck and neck, assuming he's healthy. Only thing I saw with Brion is he needs to work on his footwork a bit, but so do 99% of high school QB's.
Passing accuracy I see as
Lee
Carnes\Spano
Green
Arm strength I think is
Green
Lee
Spano
Carnes
Running ability I see as
Green\Carnes (Green more speed in a wide open field, Carnes better at getting into the open field and making people miss)
Lee
Spano
This is just my .02
I say Carnes redshirts, might have been a different if he was an early entry, but he won't pickup the scheme in fall practice. I wish Wats and Bo would just move Martinez to the slot in spring, because that's where his future is IMO and where we would actually help the team most (not that he cares).
You do not have Martinez in your rankings --- but in terms of speed and quickness, Martinez is in an entirely different league from the others --- he is considered, in pads --- one of the fastest and quickest on the entire team --- likely in the top 3-4 on the squad in that regard (at least that is what people on the team have said). He likely would be far and away the best runner of the QB's. Honestly, the only ones we have seen in action are Lee and Green running the ball. Neither is a very natural runner. Lee is a little shiftier than Green, Green is straight line faster but has poor field vision, runs straight up and down and hits defenders too high and is already falling before contact. Lee is not a natural runner either. That is, neither Green nor Lee are particularly able runners. Mobile, athletic -- sure. But dual threat --- not really.
As far as passing is concerned, who knows? Green has shown that he is really out of sorts, inaccurate and slow in delivery (mechanically) and he throws ill advised passes (it is somewhat of a miracle he did not have more picks). Then again, he was young, put in in tough situations and can, and should, improve. That said, unless he vastly improves he aught to redshirt and tinker with the notion of a position change.
I'd guess Lee is the certain starter based upon experience --- so long as he is healthy. Martinez and Spano, Green, Kellog, Washington and Carnes will compete for the #2 & 3 spot. Most likely, Carnes --- and, I hope, Green, redshirt. That would still leave Martinez, Washington and Spano as back-ups (in no particular order).