The top one is my fave. Very cute and I actually like the snow. Kinda makes it look like a postcard.
I forget to do this a lot, but in the last photo ask for the cosplayer to remove or swing the convention badge around to their back. It can be an awesome pose and great lighting but the viewer can be quickly distracted by a visible con badge.
Then again if you have a million convention photos in one folder then having badges visible can help you tell which convention you shot it at.