How about when Yoh who realizes that the only way to save Tokagero's soul, someone who has never been able to trust anyone due to his mother literally giving him her flesh so that he could survive the famine, is to place complete trust in him buy giving him control of his own body. And it works! As Anna points out, it could have easily backfired and killed Yoh, but as it turns out that what Tokagero really wanted was not revenge on Amidamaru but inner peace and love like what he felt long ago in his mothers arms. In fact the whole Tokagero possesses Ryu arc is one giant Crowning Moment of Heartwarming.
It's just as heartwarming in the anime (even without the entire backstory) when Yoh makes the proposition.
While it was a small moment, the Lily's Five standing up to the X-Laws in episode 36. All to protect Yoh and the gang from the murderous group of Shaman was very noble of the girls. Even though the ladies were way out of their weight class, it was nice to see that they actually care.
Seeing Faust and Eliza together (and I'm not talking about the creepy skeleton version).
And Faust declaring that he now devotes himself to protecting Yoh after it was revealed that Anna restored Eliza to her original form.
And their whole declaration as they prepare to fight the team of ice Shaman in the anime was just adorable.
Faust: Are you ready my love?
Eliza: My dear Faust, I will follow you anywhere.
Faust and Morty bonding over ice cream in the anime, and Faust showing that he truly has performed a Heel-Face Turn by offering Team Spartacus' leader's wife treatment after the fight.
"Amidamaru is like my brother!" AWWW!
The same episode had Faust once again try defend Eliza's honor after Foduo called her evil. Then Yoh defends her as well once she and Faust were restrained.
The climax of the Mt. Osore arc gets me Tearjerking every damn time. Anna is teetering on the brink of despair, the Giant Ogre THAT SHE created is just about to rampage and destroy everything about him, and all hope seems lost. Then along comes Yoh, wielding the Demon Slayer that Masumune pulled a Heroic Sacrifice to make. Heartfelt speeches are made, and then this line hits me:
Anna: "I love someone. And you, Giant Demon, will be snuffed out."
I liked the end of Episode 45, where we find out that Yoh and the others all took a kind of Secret Test of Character. Each of them all saw the others in need of help, but were all told to leave them behind. Of course in the end, they all refused to leave the others behind, awww.
The end of the anime series was really heartwarming compared to the manga's. The best part was the "Where Are They Now?" Epilogue and how much the lives of everyone had improved. Like how the Lily Five opened up their own flower shop.