I don't have a lot of experience riding in the snow but bought some Marathon Winter (700x35) tires a couple of years ago. They work well on ice or packed snow but not really feasible for fresh snow. Below is a picture of my first ride where I went through some virgin snow for a short stretch. Riding on that section took 300+W to go 10kph (6mph). Fun but not sustainable for long.
4-6" of virgin powder
35mm Schwalbe Marathon Winter Performance tire