Hated DS9 when it came out. Called it "Deep Space Slime". Hated the Bjorn losers, the ugly changelings, Kira, the boring space station and the lack of exploration. It was a blatant rip off of Babylon 5 and I hated that show too. Thought Voyager was better because it at least explored "strange new worlds".
But in a fit of boredom, after having watched the other series many times, and giving up on Enterprise, I forced myself to watch every season of DS9. It was a chore at first. Sisko, Dax and Quark were the only reason I kept with it. But somehow by the end of the series I became attached to all of the characters (except the idiotic changelings).
That last episode was hard to watch, not because it was bad, but because I knew I was going to miss these people and their lives. And I very much did.