Wendy, I am glad you brought up George Hall, because he is the perfect embodiment of the single quality I find most indispensable in a teacher: respect. As I think back - hankie at the ready to catch the stray tear - I can see that the common trait of the worst teachers I ever endured was their complete lack of respect for the individual student. The great teachers, the ones who made you hunger to learn regardless of their field, had in abundance the passion, humor, and connection you talk about plus - or perhaps first and foremost - a profound respect for the student.
It is this respect that allows the great instructor to listen, to carefully observe, to treat each student as a unique and infinitely valuable human being rather than as a case, a type, a capita, or a regrettable nuisance.
That's the Holy Grail of Teaching.