 If you liked
Shakugan no Shana
|
 ...then you might like
Hidan no Aria
|
The title characters as well as their male counterparts and the relationship between them are almost identical between the two managas.
Both have an even focus on action and character/relationship/backstory/plot development.
And it's all in high school, of course.
The only real difference is Shakugan no Shana has fantastical elements, while Hidan no Aria is more grounded in reality.