Teachers are with us not only at school but also at the university and afterwards because a teacher is the person whose knowledge helps me to develop as a personality. But to my mind, it is not the knowledge alone that makes the best teacher.
I must admit that the best teacher is, in my view, a highly skilled professional with a high level of competence in the subject taught. In addition, the best teacher knows how to pass knowledge in the most effective way with the help of modern methodology and technology. Also, no teacher in my understanding can be called "the best one in profession" without creating equal learning opportunities for each and everyone in the classroom.
Having described what seems to be the best quality in a teacher, I am still inclined to think that perhaps excellence in profession is unthinkable without being demanding to learners. Further on, keeping strict discipline in the classroom is perhaps essential for running a lesson. To continue, a really professional teacher always provides the learners with objective feedback on their progress.
Well, the idea of a strict teacher-supervisor has some appeal to me but on the whole I am against this role. The best results are achieved when it is not the teacher, but the learner who is demanding knowledge. When learning is really motivated, the problem of classroom discipline never arises. Talking of learner assessment, I suggest that learner self-assessment matters much more for one's progress.
To generalise, I would conclude by saying that the best teacher is not the one who knows how to teach, but who has the mastery of enabling and motivating everybody to learn.