To be fair to Cheryl, there were five girls who all had a valid claim to make the final (just Anastasia wasn't upto it). It's unfortunate that you're limited to 3 per category to fit in with the whole judges mentoring a specific category, rather than getting the best 12 remaining acts - if that'd happened, Austin might've been the only boy there!
Cheryl definitely has the three best/strongest contenders.
I agree that Amy and Hannah both might have made it if they'd been in a different category.
Amy has a lovely , pure voice. I think we may see her again when she is older and less overwhelmed by the experience.
Hannah is as good as any of the over 25s or guys.