User blog:Stellafera/What makes a good episode?

I've seen a lot of discussion about characters lately, so I figured a question about episodes instead would spark everybody's interest.

What do you think makes a good episode? Is it the challenges, even representation of characters, or something else? How does your favorite episode use these traits? How does your least favorite episode not use these traits?

All these questions and more to be answered...

IN THE COMMENTS!