I don't think it matters if they're nice people or more dedicated than the others, or more emotional. The most dedicated, emotional and nice person can still suck or not be suited for the entertainment business. Not that I adore Katherine, but she fits the bill more than the other two in my opinion.
I see Elliott as a likeable nerd with a nice voice but little or no stage presence. . Just as hard to watch is Taylor, the spastic, grimacing goofball with too much stage presence, and not in a good way!
<-----I'M TOTES ROLLING MY EYES