Do you have any particular disappointments with B5?
Me. My disappointments were not actually seeing the Vorlon Planet Killer destroy a planet. https://www.youtube.com/watch?v=Xl7C6_qa1Do
(I would like to know how it's weapon functioned. I couldn't tell if a destructive beam came from that ball of energy, or if the Planet Killer just launches that ball of energy at the planet itself.)
I would've also liked to have seen the Thirdspace Capital Ships attack. http://vignette2.wikia.nocookie.net/babylon5/images/9/9a/Thirdspace_capital_ship-01.png/revision/latest?cb=20090816000807http://www.hiperkapu.hu/sci-fi/Babylon_5/Thirdspace_Cruiser.jpg
(It would've been cool to see the offensive power of these Ships in action.)