TOS, third season, episode 8: For the World Is Hollow and I Have Touched the Sky
I also love The Cloud Minders from the same season (episode 21), but that first one gets me every time, I have no idea why.
EDITED TO ADD: I also really like most of the SNW episodes, but haven’t seen them enough times to have a clear favorite. Possibly Ad Astra Per Aspera, or Charades, lol.
TOS, third season, episode 8: For the World Is Hollow and I Have Touched the Sky
I also love The Cloud Minders from the same season (episode 21), but that first one gets me every time, I have no idea why.
EDITED TO ADD: I also really like most of the SNW episodes, but haven’t seen them enough times to have a clear favorite. Possibly Ad Astra Per Aspera, or Charades, lol.