I will agree with the Extend-A-Story Wardrobe for Sir Toby's best.  That was funny.
As for mine.
A Close Call was my first episode.  For those that like action, this is probably my best one.  
A Tender Mind Does Not Become a Sword was the one the took the most energy and thought.  One has to read it in context with the episodes leading up to it.
I have written several episodes that had their problems, but notable are: 
Notes and Plans - it took me four or five attempts to write it with the clarity required to get everyone to understand what I was trying to describe, and it still does not read as well as I would like.  I learned a lot about the pitfalls of writing on that one.
For just plain bad writing, I modelled the 'poem' in 
A Chigger's Bite after "The Tiger" by William Blake.  Read at your own risk.