Well, in the manga, Yuji has a lot of growth and potential. However, Mahito is no pushover. His cursed spirit nature and devious tactics make him a force to be reckoned with. So, it's hard to say for sure who's stronger.
Maki in fanfiction usually has a fierce loyalty to her friends, especially Yuta. She is the type to fight for what she believes in. Yuta is sometimes portrayed as being a bit naive in the ways of the world outside his own small circle, but his pure heart makes him endearing. In many stories, their different personalities create an interesting dynamic, like in a story where Maki's boldness gets them into a risky situation and Yuta's calm thinking gets them out.