I liked every arc, but the ABO was my favourite, so I often reread that part.

In the Abo arc, a lot of information about Yangyang were revealed. like his original life and his real parents, why he treasures every life he is given, why he is scared of having a child, and how he met system... It took a lot of chapters or worlds to actually get to know the main character. Because While he maybe shown as a glutton and humourous guy with a smart head, there's actually few chapters where he actually gets truly emotionally expressive without calculation. Like when he thought ml was dead, he expressed that he would not find a new father for the baby.

Yangyang fully accepted Ml abo arc too, and that was also the world where he was most reluctant to part with because he had a child.