I think it is pretty obvious that DS9 stole a lot from B5. That doesn't make it a bad series, fortunately. In time, both series took a different course; the central motive of B5 is very different.
In B5, it's about Galaxy-wide ideological struggle between two ancient races, millions of years older than humanity and other younger races. It's not about the war itself, because if either of the two races (Vorlons and Shadows) wanted it, they could obliterate anybody else, which is what almost happened in the end.
Secondary motives are civil wars in Earth Alliance, Minbari Federation and the confict between telepaths and mundanes.
DS9 has a VERY different feel to it. It's more like "WW2 in space", a story of a first real war the Federation has ever fought. It takes the Star Trek universe and explores it in depth for the first time.
I like both series a lot, and I don't really feel a need to be bitter about the fact that DS9 creators stole few ideas. In fact, I am happy: instead of just one, we have two excellent sci-fi series