>>42712702
She's humble.
Twilight was a massive introvert before writing her into a mini-Celestia, Luna was away for 1000 years, Celestia is so forced to be the mask of the perfect princess at all times that she barely has any chance to be a regular pony
Cadance was an orphan pegasus in an earth pony town who was beloved by everyone for being kind and chipper, kinda like a calmer Pinkie Pie. She was then adopted by Celestia and forced to study magic as a pegasus, which left her confused and directionless for a while, finding herself more comfortable by taking care of foals and giving them the guidance and nurturing that she wished she had. While also having a somewhat normal teenage experience growing up (going to school, dealing with classmates, falling in love, etc)
If you were to talk about your problems with any of the princesses, Cadance would be the one to be able to relate to you the most, and be able to offer you a reasonable solution from a place of sharing a similar experience. She's the most down to earth, unlike Luna, who can give you advice from a place of authority, but doesn't really know what its like to grow up as a regular citizen of Equestria.