Million Dollar Klingon (with a happier ending).
The plot is fatally undermined by the fact that we know, for certain, that Worf is going to be alive and back to normal by the end of the episode. That takes all of the emotional punch out of the ethical debates about suicide and experimental medical techniques.
If this was a movie, or if the accident had happened to a guest star, then things would be a bit more tense. But once a regular cast member is at the centre of the plot, tension is out the window.
Great Star Trek moment: the very first glimmerings of the Troi/Worf romance.
224 down, 513 to go.