My parents are favoring my sister's kids over mine and it is annoying me so much.
Is your sister and her child better than yours?
Well, my sister is less of a bitch than my parents.
I'm sorry your parents are being unfair and are having a favorite, that's very mean. You should be mad and speak up about them, they need to treat all of their grandchildren equally or else there can be a lot of toxicity and tension within the family.
They can be what they want. I'll stick to my parents.
You can stick to your parents and still be upset and offended if they are offending your sister's children. You should just tell them how you feel and maybe come to an understanding with them.