From your list:
Cadair Idris - Done but it was cloudy and would like to go back on a clear day
Moel Siabod - Not done
Pen yr Ole Wen & Carneddau - Doing on Thursday
Crib Goch - Not done and one of this years must do's
Tryfan, Glyders, Y Garn - Done Tryfan but, again, it was cloudy. Not done Glyders or Y Garn and, again, one of this years must do's
If the conditions on the day are good my vote would have to go to Crib Goch as I've been itching to do this for a while now.