I like the first image for its painterly quality and its simplicity. It has a distinct ethereal feel, like looking through a window and watching snow fall. Magical! The bottom white area balances the rest of the image and reinforces and accentuates the ethereal quality of the softness of the scene. Allowing snow to go slightly grey works well when the aim is to enhance expression, so I think the grey works fairly well and is a matter of taste. There are three slight bands at the bottom that are slightly noticable. I don't think they are that objectionable and I really like the proportions you have now, so I would not mess with it. Perhaps the digital experts can suggest something in this regard.
Re the second image, I feel the horses and tree outline are somewhat hemmed in, especially as compared to the first image. To me, the horizontal format coupled with the whiteness of the scene is asking for a more expansive view on both sides of the visible scene, so that the proportion of the whiteness (and therefore softness), to the visible scene is more balanced aesthetically. But, this is an excellent image also, and I may be unduly prejudiced by viewing and enjoying the first image so much. Cropping? Why bother, if it is not in YOUR vision. Anyone can crop.