Losing Your Star Trek Virginity

Redditor TheBishopsBane has a friend who has never watched Star Trek, but is willing to try out one episode from each series in order to be persuaded of the franchise's greatness. He asks commenters to suggest the best episodes for the task:

I have a friend who is a science fiction/fantasy fan but has never seen a single Trek episode or movie. He has become quite stubborn about it, but has agreed to watch a single episode from each series to give it a chance.

I'm looking for episodes which don't involve too much of the Trek universe's politics, don't require any prior knowledge of the characters or setting, and are just good, old fashioned story telling.

Here's my list:
The Original Series: City on the Edge of Forever
The Next Generation: Darmok
Deep Space Nine: Hard Time
Voyager: Blink of an Eye

These, I think, tell a fairly complete story and don't require as much background knowledge as other top episodes. I haven't watched past the first season of Enterprise, so I'll withhold a recommendation. And I think that The Animated Series is best forgotten, even though Memory Alpha regards it as canonical.

Which episodes would you suggest?

Link | Image: Paramount