Crystal can sing, she has quite a voice. I didn't think she had much of a singing style, though. Also, I was somewhat turned off by the whole backstory sequence. Getting a tattoo, etc. I don't know why, it just didn't endear her to me for some reason.
Didi is talented, also has a great voice, but she's not my kind of singer. I'm not fond of that pseudo-folk, Feist-type style, and the falsetto singing. It's a fad that I hope dies soon.
So I guess we disagree on those two! I'm sure they'll be around for quite a while, though.
Nobody really had "star quality", to me. Good singers, but that's not the same thing. I'm not sure I saw any TV stars tonight (and that's part of what AI is about).