I have been a huge Babylon 5 fan since the show first aired over ten years ago.
When most people think of a sci-fi TV show, Star Trek probably comes to mind first. The original Star Trek (and its spin-offs) set standards for the whole TV sci-fi genre. It has also, in many ways, become a very cliched, unoriginal, and repetitive franchise, in my humble opinion.
"B5" was a sci-fi TV series with a number of significant differences.
First, it's pretty obvious to me that B5's creator, J. Michael Stracynski, was heavily influenced by the famous epic novel, The Lord of the Rings. B5 is similarly large in scope, and there are structural and characteristic similarities between his races and Tolkien's. Place names in B5, such as Zahadum, the home planet of the Shadow race, are phonetically similar to Kazadum from LOTR. The Shadow vessels in B5 shriek, not unlike the Nazgul of Mordor. Oh yeah - and Marcus from B5 is a "Ranger" (and could also be mistaken for Aragorn if I squinted a little).
Now, what about the differences between B5 and that other mega-franchise, Star Trek?
Overall, I have found that Star Trek and it's spin-offs have little, if any, continuous storyline between episodes. Each episode is largely self-contained and usually resolved within the hour. B5 has numerous continuous plotlines that continue through the series' entire 5 year run. Secondary stories and characters are also integrated into a hierarchy of events, adding depth and realism to the main plotline.
In terms of makeup and special effects, I also find Babylon 5 to be superior to the Star Trek franchises of the time.
When channel surfing, I can tell a Star Trek episode by the alien races - the forehead or nose appliance the actors wear. It has become such a cliche of the show. B5, on the other hand, always used elaborate makeup for all the main alien characters. Only in recent years have Voyager and Enterprise begun to use more elaborate and convincing makeup for important alien characters.
Basically, Babylon 5 was an extremely well written and well produced sci-fi drama, and even though it's been off the air for years now, man alive, am I ever enjoying the DVDs! :)