Casey is perhaps the best overall performer/entertainer but does he have the "it" factor to make it big and not become Taylor Hicks (who I never really got) part II?
Thia has my favorite voice to listen to and excellent poise for 16 years old, but she may be a few years away from having the total package needed to go over well as the AI.
Jacob I think has unique raw talent and potential if harnessed properly by the right people.
Pia is a likable hottie with a great name, definitely can sing till the rafters come loose, and has the "it" factor. Fergie, move on over....
Haley may also have the "it" factor needed to make it big in modern pop music. As you can see, I am always partial to the girls when it comes to these things....
Naima also has the "it" actor to perhaps make it big, but needs some polish.
Scotty has what it takes for a nice career in country music I would say.
James Durbin has potential....
The rest I am less sold on as future stars though they all have talent and can sing.