Much as I’d like to, there are too bloody many GOOD episodes of TV out there. Here are a few of my favourites, but I don’t think I could pick just one.
“The Gift”, season 5 closer for Buffy. I literally cried out “No!” when she went off the tower, and spent a good half hour alternating between crying and staring in shock. “Becoming, Part II”, “Hush”, “Once More with Feeling”, and “The Body”, of course. All gut wrenching episodes.
“Z’ha’dum”, the season 3 ending for B5, mostly for the look on Sheridan’s face as he confronts Anna, his feelings for who she was, and his repulsion and grief for what she’s become. “The Hour of the Wolf”, the next season’s opening episode, where Ivanova tries to pick up the pieces after Sheridan goes to Z’ha’dum. Several other B5 episodes already mentioned, including “Passing Through Gethsemane” and “Sleeping in Light”.
Many MAS*H episodes, including the “interview” episodes (the one where Father Mulcahy talks about watching the surgeons warming their hands over the wounded soldiers’ opened bodies is mind numbing), “Abyssinia, Henry”, and the one where the entire episode is done from the wounded soldier’s point of view.
The “wrap-up” movie for Homicide, the scene where Bayliss confesses to Pembleton that he murdered the drug dealer/murderer who got released on a technicality. And then G dying after all.
And, just so no one gets the idea that the only kind of TV show I like are the gut wrenchers, almost any episode of “As Time Goes By” and the Victorian Christmas special for Black Adder III (I think), where Edmund gets a glimpse of the possible futures, a la Scrooge, and then winds up telling Queen Victoria herself off.
Lots more in mind (Cagney & Lacey, Quark, When Things Were Rotten, Xena, etc.), but I’ve gone on long enough.