Simply state your favorite episodes from whatever series you want and why you look it so much. This isn't a contest or debate so try to keep the criticism down. I'll start...
"Scenario for Bloodshed" - Gundam Wing
This is easily my favorite episode in the series. Up until this point, the series had been a bit uneventful with only a few noteworthy developments. However, the story revved into full gear in this episode. The Gundams are tricked by Treize into attacking a base in New Edwards where Alliance leaders looking for peace are meeting. Heero ends up delivering the blow that really shifted the power in Treize's favor. Simultaneously, OZ's coup d'etat against the Alliance, Operation Daybreak, is launched and the majority of the Alliance is quickly toppled. The icing on the cake was using Septem to declare war against the Gundams and the colonies. I've never been a big fan of Treize but you can't help but be impressed with how his schemes came to fruition in this episode.
"Duo, The God of Death Once Again" - Gundam Wing
This was the second favorite episode in the series. Duo Maxwell got the majority of the screen-time but there was also an interesting part of the episode early in the episode where Sally Po and some former Alliance members search for Wing Gundam in the sea. I actually gained more respect for the Alliance after they lost power and I found it cool how they assisted in the fight against OZ. Back to Duo. He's actually my second my favorite character in the series and I liked the focus on him the majority of episode. Not only does Duo go through a lot during his mission but he manages to convince OZ recruit Hilde to give up her life as a soldier and live her own life. There's a lot of flash in this episode and Duo ends up as prisoner in the middle and at the end of episode() but it's still a great 20 minute ride that shows how good a soldier Duo is.
"Time, Stand Still - Mobile Suit Gundam"
I watched this episode two day ago and it's my favorite so far(I'm only 16 episodes in). While nothing really big happens in the story, I really liked how this episode gave almost equal focus on the White Base crew and the regular Zeon soldiers. I knew that Amuro and Co. would get all the bombs off his suit eventually but I definitely didn't expect the final scene where the Zeon soldiers dressed up as civilians and mockingly gave Amuro support. The tension during that scene was powerful and very well done.