As an ardent fan of TNG,
I loathed DS9 when it first came out, as the whole "immobile spacestation" concept struck me as very much not Star Trek. The first series was a bit ropey (Dr. Bashir was just unlikable (probably suffering in comparison to the fantastic Garak!), and watching Avery Brooks chew up the scenery was at once hilarious and tragic) but, once it hit it's stride, it really was an excellent show. Shame I never saw the conclusion (think I stopped watching after it was alleged that Gowron had been replaced by a shapeshifter*), but I think it really was the equal of TNG, afterall (unlike Voyager, which was pants, and we can all pretend that Enterprise never happened).
*nothing wrong with the storyline but, as I was 15 when it started, I assume that I must have moved on to other pursuits by this point!