What I loved about Babylon 5 was the wonderful concepts. They had some really amazing concepts. What I couldn't stand about B5 is that most of them got dropped halfway through like a sack of potatoes, never to be revisited again. There were only a couple of arcs that seemed to play themselves out completely, like "The One."
What I loved about DS9 was that even though they didn't deal with as many great, larger than life, concepts, they managed to do more with the less that they tackled in terms of things playing out to some kind of satisfying resolution. Even though things weren't as planned as B5, this series took some time to work on what it did and that showed. Plus, the look of it was better.
DS9 had the better cast, but B5 had some wonderful and intriguing aliens in Londo, G'Kar, and Kosh. I also liked the human cast as well. Both the Dominion and the Shadows had their strengths and weaknesses, but I like them both equally, so I voted for them both. DS9 had the better commander in my book.