I actually like kyoko's backstory.  How she made her wish for her father. It made her the character she is and kinda shows why she's always eating something and mean.

Also it gave more about how every wish always ends up being bad. If you think about it all if them have a good backstory. Like mami she only made her wish so she wouldn't die and humora so madoka wouldn't die. 

They did a great job with the backstorys.