I want to give kinda honorable mention to the episode "Paradise" where Sisko and O'Brien land on a planet where technology doesn't work. The leader - Alixus - becomes almost obsessed in forcing Sisko and O'Brien to give up technology themselves. While I really enjoyed the episode, I was so disappointed that Alixus didn't get the comeuppance she deserved. Her villagers accepted what she did to them and even validated her views. And while she may have had a good (if stagnant) society going, I was so outraged by her psychotic need for control and that she took away their choices. And she was not at all remorseful. For such a good episode, I was left feeling very dissatisfied and frustrated by that ending.
O'Brien is off on a vacation with his wife when he gets arrested by Cardassians for a crime they don't feel the need to inform him about, to put him on trial for which he is already assumed guilty. The Cardassian justice system is no joke, as it seems mostly about encouraging the accused to 'fess up to their crimes and atone so that the Cardassians viewing the trial can feel better about themselves. The reason I enjoyed this particularly is because of O'Brien. O'Brien is a flawed character - he has his prejudices and he's not always the nicest, but he is a good person, and seeing him treated so unjustly, and how frustrating his situation was, made him so sympathetic. And the trial was extremely frustrating in itself, that the satisfaction of Sisko showing up in the end and ruining the whole thing without saying a word was very fulfilling.
Another O'Brien-centric episode! In this one, O'Brien is being treated very differently by everyone aboard the space station from Sisko to his own wife and child, and he has no idea why. The twist in this one is pretty mind boggling, and I loved how the story is told from O'Brien's perspective when it could have been told from a different one. The storytelling is the highlight of this one, especially because I had no idea of how it would end - the episode was getting close to it's finish, and I couldn't imagine what was behind the door in the last scene that would explain everything. But boy did it.
3. Armageddon Game
O'Brien (again!) and Dr. Bashir are helping the Kellerans and T'lani erase the existence of a biological weapon to stop the fighting between the two races, but are then attacked right when they are finishing the job. O'Brien and Bashir's rocky friendship is a great part of this episode - especially since in this episode they grow to appreciate each other more. O'Brien is accidentally infected by the biological weapon, so there is that added suspense (although of course he would be okay) of O'Brien needing treatment asap. I found this a great story with fantastic character development. And O'Brien's defense of marriage was so heartwarming!
This episode references the Original series episode "Mirror, Mirror" where Kirk and crew go into an alternate universe and encounter a darker version of the Enterprise. Kira and Bashir are the unfortunate crew members to enter the alternate universe this time and it is just as dark and disturbing as it was so many years after Kirk went through. Seeing most of the DS9 crew in such altered personalities was a fun part of this episode, even though it is pretty distressing how bad of a situation these people are in. I love episodes that are a nod to the continuity of the Trek universe as well, so that's another reason I enjoyed this episode so much. And I thought Nana Visitor was so compelling as AU Kira.
1. Necessary Evil
A seemingly mysterious attack on Quark, reminds Odo of an unsolved murder from the days of the Cardassian occupation, and Odo investigates the case again, bringing up a lot of memories. There are flashbacks in this episode to when Deep Space Nine was run by the Cardassians and it was not a great place to be. I thought seeing the recent history of the space station through these flashbacks was a great idea since it added layers to the characters and the stories they tell in this series so far. It's really grim to see Odo cowed, and Kira downtrodden but it makes it even more understandable why they are good friends now. The character development for Odo was a highlight for me, as was seeing him solve this cold case with it's surprising solution.