I’ll start - S02E09 Measure of a Man
This is my favorite TNG episode for a couple of reasons. First, it shows that they didn’t need amazing effects and set pieces to drive the story - most of this ep consists of the actors sitting in a single set and talking, yet the story is still fantastic and the episode is riveting.
Next, this is my favorite because Data is my favorite Star Trek character overall, and I feel this episode is a key piece of his character’s development.
An ambassador aboard the Enterprise is revealed as a spy. At the same time an event happens with the ship that was possibly sabotaged.
If you don’t remember past that I really suggest watching it!
ohhh yes, with the inquisitor lady who gets called out of retirement