In the 7 years I've been here, I've never really seen the superiority complex that others saw in TNG other than in the first two seasons. Granted, maybe it's there, and maybe I just look at TNG in the whole "rose-colored glasses" (Since I grew up with it) but in the later seasons I didn't really see much of it. What I did see is a series that expanded on the universe that Star Trek created, and really gave the federation more teeth.
With DS9, the same can also be said, and I think both TNG and DS9 compliment each other very well. If TNG gave us that federation utopia, than DS9 expanded it to give us the other side. Ira Behr always brings this up and I agree with it, but the quote in Maquis, "It's easy to be a saint in Paradise" really is what DS9 wanted to accomplish. If someone asked me what is one thing that you would say DS9 is about, I was say that quote. It's the underlying theme of the show, it was just really awesome to see it explored.
DS9 also expanded the universe that TNG continued. It made it more organic, more real, and a lot more interesting. This is really why I absolutely love 90's Star Trek. It was a progression of the entire universe, covering all the basis and I was very interested in that. I like that the studio's brought Star Trek back to the masses with a reboot, and the whole debate on what Abrams did still continues, but I miss the 24th century universe. Star Trek was always about moving forward, and for 16 or so glorious years, it did just that. I miss it so much.