To elaborate on my criteria: these should be episodes that can work with a minimum number of sets, no special effect and modest-to-minimal practical effects, and amateur though dedicated actors.
Two examples come to mind.
The first is TNG’s “Measure of a Man”. This episode is almost entirely dialogue and takes place in large part in a single conference room. You could probably do a pretty straightforward 1:1 rendering of this episode on stage.
The second is DIS’s “Species Ten-C”, in which the crew make first contact with the titular species and determine how to communicate. This would require more creativity on the part of the production, but given that the 10-C communicate using light, I imagine that even an amateur production could do something compelling with practical effects.
I’ll admit that I am biased: I think I tend to prefer episodes that meet these criteria. I like my Trek talky and tend to have a soft spot for sappy and hammy episodes. But what intrigues me further about these stories is their ability to pass into cultural myth. I’m not saying that these are the only episodes that could transcend Trek and move into the cultural fabric of the era (think of Luke Skywalker and Darth Vader), but they seem like they might have the best shot.
What do you think?
Well, the OP spelled out their criteria explicitly.
these should be episodes that can work with a minimum number of sets- In The Pale Moonlight could work on a single set. It’s Only a Paper Moon could work with two. DS9 and holodeck/Vic’s club.
no special effect and modest-to-minimal practical effects- In both cases the episode is carried out through dialogue.
amateur though dedicated actors- This one’s a little harder to quantify, so I’ll leave that up to OP’s judgement.
In addition, they deal with themes that are relatable without being exposed to the context of the story. Moreso It’s Only a Paper Moon than In The Pale Moonlight.