* The Naked Time - a great example of how to show repressed sides to new characters, where even split-second one-off figures like the graffiti guy who paints words on walls leave one asking for more... but in a way that lets audiences embrace the show and figure out possibilities and ideas for themselves (head canon? fanon), which is far more satisfying as well as one letting it be as complex, convoluted, or simple-dee-dimple as they want.
* Charlie X - not your father's coming of age story... has aged by and large extremely well
* The Man Trap - oversimplified and plot easily avoided if he brought down the dang salt, but is an early example of showing compassion to endangered species... even if Kirk and his viewpoint aren't incorrect (nor disproven)... critics were lukewarm back in the day but for its simplicity it's still fun to watch just for the monster costume design, which is really good. Uhura gets a brief moment when the salt critter turns into a hawt guy and the Swahili spoken is actually quite soothing to my Vulcan little ears..
* The Conscience of the King - um, metaphors for throbbing engines and stuff (which also ties into the same theme as "The Enemy Within"!) aside, it's remarkably entertaining... reminds me of "British Shakespeare... in Space!" or half of Blake's 7 series 2...I don't know why...
* The Enemy Within - despite failed punting with shuttlecraft issues and while being the first "the transported caused the plot" trope in Trek's history, it's still - where it counts - a solid and frightening take on how the weaker, emotional side of us is actually the stronger in keeping the savage side contained. Early TOS did embrace horror...
* Balance of Terror - a robust cat vs mouse game, but proverbially leaving unused doors wide open
* Miri - eww, I did not sign up to see "daddy action" that Miri seemed to be hoping for... if Miri knew where Kirk was she might not either, unless she still wanted to as there's no right or wrong way to consider everything
* The Corbomite Maneuver - it had much more impact in 1966, about deceiving size and power. It's still a good episode and great for the time