I'm not as "emotionally invested" now that my favorites are gone (Michael Johns and Carly Smithson, who sang together on "Ellen" yesterday, BTW), so I'm watching only half-heartedly. I think all 4 of them have talent, but each has a definite style that may or may not appeal to everyone. In terms of who's the most versatile and marketable as a pop/radio star, I think David Cook is the most ready for that path. I rarely dislike his performances, and he has more maturity and confidence than the other David for being able to handle what would be ahead for the winner. He's also more interesting to watch - he's not just a ballad or "feel-good song" type like David A.
I admit that I like Jason - I like the folk style he gravitates to, and I think he's very humble, but he definitely doesn't deserve to be there any longer. I agree that it seems like he doesn't want to win, he looks like he couldn't care less about being there. Maybe he knows it's not his element and that he's better suited to the small-venue lifestyle, not the huge pop star thing.
I don't always like Syesha's performances, but I think she definitely wears the most beautiful outfits week after week. I felt bad that her tears were destroying her make-up last night -- for her sake, I was wishing they'd quit putting the camera on her. It was literally running down her face.