I like all of the above suggestions and find them of merit. I'll add one that most will probably not mention from an episode that's not well-loved, the final moment of "Requiem For Methuselah."
After Kirk's wish to "forget" his recent ordeal, and McCoy's echoing of that sentiment, Spock takes it upon himself to grant his friend's request. It was a moving moment in the series, and one that I will never "forget."
I thought that scene was pathetic, and best forgotten (no pun intended). The Kirk I remember isn't the wimp who wants difficult memories erased so he doesn't have to face them - he's the man who told Sybok where to shove his mind tricks, and that he defines himself by the right and wrong
choices he's made in life. By the good and painful memories. "If we lose them, we lose ourselves"