Tubby Wubby Pony Waifu. A surprisingly sweet love song, especially for one about a magical blue pony and an evil monkey in clown make-up.
Made even more heartwarming when you learn that the two singers started a relationship during its production.
I don't know why, but I find this comment from this video strangely heartwarming: "No RDP cheating! RDP will be made on the basis of love and whatever other emotions we keep using. Gorillas and stuff. Gorillas are emotions. I feel strongly about Gorillas. RDP is not for sale! I will use the voice, though."
"Sinking Ships," a song about not letting life get you down. Especially heartwarming (And a bit tearjerking) considering this is the last Rainbow Dash Presents.
Good news! Petirep has announced the start of work on "The Star In Yellow", so this may well no longer be the last episode.
With everything Fluttershy has to go through in this series, Rainbow Dash and Applejack are the only ponies that are nice to her.
Along with Celestia for at least a whole conversation.
In episode 14, Rainbow Dash tells Fluttershy she'll save her if she falls and forgets she has wings, like when they were kids. It's kind of sweet to see that she has, at least one genuine friend.
Episode 22 is pretty much just a long, mellow conversation between Spike and Twilight where they both display that they care for each other as friends. Twilight essentially says she appreciates Spike's help, and Spike says that his concern about a possible conspiracy surrounding Twilight "keeps him up at night".
From the negative episodes: Thrackerzod is apparently aware of the series rebooting. What does she do? Confront Apple Bloom so she can reform the crusaders, implying she actually does enjoy their company. She even makes sure they adopt the same name.
Also from the same episode, Apple Bloom and Diamond Tiara managing to get along.
In RD Presents: My Little Dashie, we are given Rainbow's relationship with her adopted father, sole friend, and her twisted romance with the Jokermort.
Also, the rest of The Mane Six, actually came back for her.
Not only that, but sense she didn't earn her Cutie Mark on Earth, the epilogue shows Rainbow Dash briefly joining the CMC.-
Whenever Rainbow finds some form of happiness, during the Let's Ramble Over Fallout New Vegas videos. Considering how being in the Mojave, it is very touching to see her still find enjoyment in the world.