Ok, here I'll discuss the princesses
First, think about the thousand years Luna was banished. I can't imagine the pain Celestia would have felt for those many years. Everyday, she raised and lowered the moon. Her sister's shadow looking down at her. Every year, the ponies celebrated the defeat. Celestia was constantly reminded that she was not able to save her sister from herself. To many of the ponies, it was a glorious defeat. To Celestia, it was the loss of her only sister. There no way I could imagine living like that for so long. Another point, celestia has only cried twice, being reunited with Luna and when she banished her.
Luna, I can relate to in a way. I've been badly bullied and i can tell you, pain will turn anyone cold. Luna wasn't "evil", she just felt like no one cared about her glorious night. During those months of bullying, I felt unwanted. I loved listening to fan made luna songs like "let it go" and "lullaby for a princess" or even "the moon rises". In "the moon rises", I especially related to this part "am I so wrong to think that they might see things like I do and am I so wrong to think that they might love me too, why shouldn't they adore me, is it not within my right? I will not be overshadowed, mine is not the lesser light".
Cadence, is my other favorite. Not much to evaluate about her. She a sweet, but strong princess. She is definitely pretty.
Please leave opinions and anything you'd like to point out about the princesses