Myrkin, I haven't watched the movie or the series, so I'm limited. However I always enjoy those moments where characters have those life altering moments myself.
The most classic for me was watching Darth Vader find the good in himself to save his son from his master.
As far as WSD moments go, the saddest and most bittersweet moment for me occurs when Holly tells how the Sandleford Warren was destroyed by the humans. It was such a brutal graphic portrayal of what happened to their home and the title of the chapter "For El-ahrairah To Cry" was fitting. At the end of the story Holly says:
"You can imagine what it means to Bluebell and me to find ourselves underground, among friends. It wasn't I who tried to arrest you Bigwig - that was another rabbit, long, long ago."
How sad. It's also another one of those self-realization moments we were talking about, of how one was before events changed them.