Undiscovered Country is even better if you watch it in the original Klingon.

I can understand why. The motivations and message are a bit deeper than WoK. But UC wouldn't have happened (in the same way) without WoK first, since I don't think Kirk had the same hatred towards Klingons before. Distrust sure, but not revenge level hate.

UC also has that connection with one of the best TNG episodes, Yesterday's Enterprise.

I'd put it above all the TNG movies, too.