Well with Season 2 you got episodes by a variety of write r's, bu then I think the last five were written solely by JMS, which leads into both Seasons 3 and 4 which were completely written by JMS as well.
But, just on a slight OT note, another great Sci-Fi series to watch (and which unfortunately only has 2 of 3 seasons on DVD) along with B5 is seaQuest DSV
(third season was renamed seaQuest 2032
). "seaQuest" originally ran from 1993-96.