For me DS9 was, and still is, the best of all the "Trek"s. It's more intelligent, dramatic, humorous and darker than the others. It holds up a mirror to prejudice, politics and religion like none of the others ever did. It has more conflict between the characters which allows for far more involving drama. All set against a galaxy of familiar and unfamiliar races with the ominous clouds of interstellar war gathering from the end of season 2 and exploding in season 4. The battles in space are the best in the series. The storyline is convoluted with dramatic twists and turns with each episode. It also gives the better insights into alien societies than the other series managed to do.
This was a great purchase. Hours and hours of great entertainment that manages the rare feat of a TV series still being as good as you remembered the first time you saw it.