I'm taking out The Wire. Great episode, but it is very bottle like. It rests heavily on Robinson, although the other performances are still strong.
Necessary Evil
Why I chose Necessary Evil over The Wire? Necessary Evil is DS9's origin story. It explored the long standing relationship between three major characters and one recurring character. It got to the problem of truth and realism that would become a core theme throughout the series. It is also a great noir story, perhaps the best Trek ever did. And it also had some great comedic moments that did not undermine the seriousness of the investigation.