I'm hoping/expecting everyone generally to improve next year (aside from maybe C-ute who are already excellent), so I'll try to mention only some specific special cases.
I'm thirding Maachan
She's been doing so well that you can't help but become excited of how that's going to continue, etc.
I've started to see Takechan as a sort of reliable Gaki-san type performer/character, so maybe in some way I'm looking forward to seeing more of her in that way.
And ANGERME in general excites me.
From Country Girls newbies, I'm looking forward to Nanami Yanagawa's first appearance in the group especially, or rather, I'm curious to see if anyone is really going to stand out in the group next year. Chisaki is my fav, but that doesn't mean I'm not open for others shining in the group.
And yeah Kobushi Factory has my interest, too! I'm looking forward to more strong voices and their growth as performers.
With the newbies it's a bit hard to say something concrete because there are so many sides of them we haven't seen yet, so the potential for them to surprise us is great, but - it'll be a surprise...
Oh yeah, I'd love to see/hear Aarii continue improving her vocals because that was a nice surprise for me this year.