The most enjoyable episode for me to work on was probably Durotan. This is pretty much entirely due to the subject matter (I love me some wolves), and the schedule at this point allowed this to be the only episode whose final art I worked on pretty much on my own. The simple needs of the story helped this. When your backgrounds are just trees and snow, you can concentrate a lot on the characters and action without getting bogged down too much in the ambience of the situation.
Don't get me wrong, ambience is awesome, but when you've got to finish 91 shots in 6 weeks, it's nice to embrace the simpler side of things.
SPOILERS BELOW THE LINE
Watch first if you care to!
Also around this time, Blizzard's wonderful Video and Post Production department were making a couple of "Behind the Scenes" videos to accompany the series. They didn't end up getting released till after all 5 episodes were already out, but they made one consisting mostly of yours truly talking about art things.
Let me tell you -- it REALLY helps to have an awesome editor/interviewer that will ask you good questions and later edit out all your various ums, ahs, and awkward pauses. He managed to make me sound like I knew what I was doing. You're the best, Lucas!
I can't help but feel more connected to Durotan as a character after drawing him so much. Funny how that happens, really.