Her tribute to the late Jeanne Manford, the founder of PFLAG. Plus the fact she admits that crying isn't a bad thing.
Doubles as a Tear Jerker, is her interview with the parents of one of the slain children at Sandy Hook Elementary. Watch here and here.
On a related note, following the release of the 911 calls of the day of the shooting, she swore that the show would not play any of the recordings, citing that they had nothing to contribute that could not be obtained in transcripts or interviews of those who had listened to them, and she does this on air, in a voice of smoldering anger at the fact that they have been released.
This extends beyond just 911 calls. Rachel hates the news media's tendency toward Bile Fascination, and so she absolutely refuses to join her colleagues in it. This includes her strict ban on any video or audio clips from the hostage executions carried out by ISIL during the Syrian Civil War, even when everyone else in the media (including her fellow MSNBC commentators) has done so.