We love bth HSM and Hannah - honestly if you watch both (and believe me I have) there is really very little negative to be found in either.
HSM shows how kinds from all different "groups" at school can come together and enjoy the same things. The basketball hero makes the lead in the school musical along with the smart scholastic bowl girl. They both are shown going against what their friends believe because the musical is what they really want to do. In the end, all of therse kids become friends regardless of their likes and interests.
Hannah really does have a good message if you watch. While she is very popular when she is performing as "Hannah", Miley is an outcast at school, chosen last for gym class, bumped to the worst locker so the new cool guy can have hers, the popular girls don't like her, she's just your average kid. She chooses not to let everyone know about her "Hannah" alter ego because she doesn't want kids to like her/treat her differently because she is a celebrity. She wants to just be a normal kid. She lives in a single parent household and honestly, and talking back to her father is minor and is always followed up by an apology or talk with her dad.
Honestly, there are many more cartoons out there that have a much worse message than HSM or Hannah. (And I really like the songs in both!)