Haven't posted in this forum in a while...but here goes. Yes, there are so many good ones, and yes all the typical popular ones have big "wow" moments and are backed to the brim with good stuff. Fall of Night, Severed Dreams, Z'Ha'Dum, Sleeping in Light, etc....but I really at this point am not going to say any of those are my favorites. Main reason being, and someone above said this, that I have watched those to the point of not being blown away by them anymore. And when you watch a "wow" episode too many times, it loses its punch.
So for me I'm going to go with:
"In the Shadow of Z'Ha'Dum"
It wasn't a "wow" episode per say. It did have lots of neat reveals in it and story elements, but clearly wasn't meant to be on the level of the previously mentioned episodes for sheer "wow" factor. Here are all the parts that make this one awesome for me:
* Nightwatch rearing its ugly head for the first time
* Kosh and Delenn revealing the First Ones for the first time
* Sheridan going irrational on Morden, to the point of alienating himself from his entire staff
* Sheridan REALLY showing is ugly "win at all costs" side by using Talia
* Talia slapping Sheridan
* Vir's standing up against Morden and showing no fear...and his foreshadowing "wave"
* Sheridan's WW:II Coventry speech to Zach while watching Morden on the screen. That one still gives chills.
* Sheridan seeing Shadows for the first time.
* Seeing Anna Sheridans fate tied to the Shadows for the first time.
* Franklin showing the first signs of trouble with working long hours and stims.
This one just has some great parts of the B5 story in it that all equal a cool episode while still being off the "super momentous episode" radar. I just like the way this one flowed and its overall feel.