We don't really know. Has she ever even mentioned one parent without the other?

Yeah, She never mentioned that whom does she loves more!

I was just thinking that, for example, if she talked more about her mum and spoke more about spending time with her rather than her dad, it'd be a clue. But that's not the case.

Every example I can think of where Hermione's parents are mentioned, it's together. When they're in Diagon Alley in the second book, when she talks about how they're dentists and didn't want her to magically alter her teeth, when she talks about having altered their memories to protect them.

father <3

She talks more about her mom.

It is a prove that her mom is closer to her

^When does she talk more about her mum? I can't remember any examples where one parent is mentioned without the other!