What are your favorite episodes of Star Trek?

We've had quite a lot of Star Trek produced over the years! The last I had seen we're well over 900 episodes and counting. There have definitely been a lot of episodes that weren't that good, but we've also had quite a few episodes that are pretty great! What are your favorites?

I always have issues with narrowing things down, but these are the episodes that immediately spring to mind:

• DS9 1x19 Duet
• DS9 2x22 The Wire
• DS9 7x10 It's Only a Paper Moon
• TOS 2x06 The Doomsday Machine
• TNG 3x03 The Survivors

After writing down those episodes and thinking about it a bit more, I also thought of these as well:

• DS9 4x19 Hard Time
• TNG 3x23 Sarek
• DS9 6x19 In the Pale Moonlight
• TOS 1x14 Balance of Terror
• TNG 2x09 The Measure of a Man
• DS9 4x02 The Visitor
• TNG 4x02 Family

There are certainly more I haven't thought of so the list changes sometimes, but it's at least the list of the episodes that I remember most!