Which is tougher???

The new semester classes would start from tomorrow. At this juncture, there is one thing that I am wondering about.

Which is group of students is tougher to teach. A group where the students do not have a clear idea of the basics of the course? or a group which has many students with a quick grasp of the course and who surpass understanding the content of the course and prefer discussing nuances of the subject, something about which you may not have a clear idea.

Only time will tell...