What is the name of the author who teaches the most courses? | Which kinds of names do you prefer? | personal name
SELECT T1.personal_name  FROM Course_Authors_and_Tutors AS T1 JOIN Courses AS T2 ON T1.author_id   =   T2.author_id GROUP BY T2.author_id ORDER BY COUNT ( * )  DESC LIMIT 1
author who teaches the most courses refers to the author with the maximum number of courses; personal name is the preferred output.