Before I was as much a fan of B5 as VoA, I was pretty into DS9 at the time and while I admit that both shows are great, it should be acknowledged that some plotlines for DS9 were at least influenced by B5. Fans are well aware that JMS (creator of B5) didn't just pitch the basic premise of B5 to Paramount(?) Execs, but also much of the 5 year story arc. The studio then rejected his ideas only to produce DS9 a few months later with not just a similar setting but also character and plot development as well (Minor spoiler for anyone who can't see the Emissary/Valen connection amongst many such spoiler-laden examples) It's because of this that some changes had to then be made to B5 a year after DS9 premiered to differentiate the two.
In fact, even though B5 is a great show it could have been so much better if it hadn't been for rewrites to the original plot (by one person as opposed to a team of writers) due to 3 main factors:
1) Supposed "plagerism" by DS9.
2) The late Michel O'Hare (Commander Sinclair) having to leave the show after one season due to Mental Illness.
3) Studio Execs being non-committal to renewing the series at the end of every season.
Despite these hurdles, it's a true testament to the writing skills of JMS that he was able to produce such a great show that was so far ahead in its time.