The characters. Daniele Steel creates very relatable characters. Readers can see themselves or people they know in the characters, which makes the stories more engaging.
One of the popular ones is 'The Promise'. It tells a story full of love, hope and family relationships. The characters are well - developed and the plot is engaging.
I think Christmas piano cartoons that have a heartwarming story behind the music tend to be well-liked. Maybe like a group of friends coming together to play piano for a charity event during Christmas. Also, ones with colorful and magical settings can attract a lot of viewers.
You could have them constantly trying and failing at diets or exercise routines in a hilarious way. Or maybe they have a love for food that leads to funny situations. Another option is to have other characters' reactions to them be funny, like being overly shocked or scared of their size.