I think when looking at the physical gifts of a quarterback you have to take into account what he does with those skills.
Michael Vick has incredible speed, agility and a big arm. He however has proven to be a below average passer.
McNabb has very good speed for QB, good agility, strength and very good arm however he is a passer 1st.
I'm not sold on the very atheletic QB unless he is more Steve Young than Michael Vick. I don't know enough about Russell to say what he is either way but he should be working on reading D's, progressions and touch passing more than anything else.