For the professors who advise more than 2 students, which professor has a higher teaching ability? Give the full name.
professor advising more than 2 students refers to COUNT(student_id) > 2; higher teachability refers to MAX(teachingability); full name refers to f_name and l_name;
SELECT T.first_name, T.last_name FROM ( SELECT T2.first_name, T2.last_name, T2.teachingability FROM RA AS T1 INNER JOIN prof AS T2 ON T1.prof_id = T2.prof_id GROUP BY T1.prof_id HAVING COUNT(student_id) > 2 ) T ORDER BY T.teachingability DESC LIMIT 1