James Newton Howard is missing that "umph" we need.
Zimmer is all "umph" and lacks finesse and melodic skills.
Powell is an interesting choice and I can't believe I didn't think of it. He needs something like this to REALLY sink his teeth into to really shine because his resume is somewhat lacking in the action adventure department. I'd love to see what he could do with William's themes. Speaking of themes, I'm guessing there will be more returning in the new trilogy aside from just the regular Star Wars theme, most like the Force theme (Binary Sunset) and quite possibly some of the Rebel Alliance motifs brought back. If Leia's back it will be really nice to hear her theme again with her onscreen (it will help with the shock of seeing the character all old and scraggly)
I know most people might not think that the romantically-driven modern day Avatar and Titanic type James Horner is the right choice for Star Wars, but honestly he is THE MOST diverse composer out there today and if there's one person who can get back into those old fashioned, melodic and thematically-driven film scoring techniques that were so prevalent back in the day it's him.