While it would be cool to be a mermaid, I think Jasmine is a better option. She's got the Genie, the carpet, three awesome (and most likely trained) animals, she lives in a warm climate, has an awesome wardrobe, and her guy is Aladdin. Who wouldn't want to be Jasmine for that alone
In reality, however, I'm like Cinderella before she married into royalty...I doubt that counts for anything though