Top 3 (in no particular order) and why:
*Mulan. She's kick @$$, beautiful, and so AWESOME!!
*Stitch. Stitch cute and fluffy. Stitch found his family all on his own. It's little and broken...but still good. Yeah, still good
*Belle. The only (true) princess I really like. I can relate to her in so many ways. She has a more...natural singing voice than some of the older princesses, such as Snow White or Aurora (cannot STAND their singing voices) and she's the most likeable for me.
Oh, and why do they consider Mulan as one of their (many) princesses? She's not of royal blood, in fact, she's a commoner, and she marries a general, so she's not royal by marriage either (like most of the other princesses). So what's up with that?

(I consider her a heroine, personally)