There are more Mary Sues than Gary Stus in fiction because women aren’t written as people I’m a lot of media, so they aren’t allowed to have the realistic flaws that keep them from being Mary Sues.

Light is a power fantasy, but I wouldn’t call him a Stu because he’s a megalomaniac and has an actual personality. He also fails at the end.

Stark has his own personality issues, but some of the TV shows fail to highlight those so he does come off as a Stu.

The biggest Mary Sue and Fary Stu genres are romance where you’re supposed to self insert, so the MC has to be very plain and boring and just like the reader or viewer. Romance novels for women and harem anime for men.