The Lake MXZ303 is a subzero rated mountain bike shoe. Comfort is outstanding in the 303. The neoprene around the cuff allows good movement while pedaling. The shoes also did not feel overly bulky when riding and had no issues with rubbing the stays. The Boa and velcro straps offer plenty of adjustability to dial in your needs. I’ve only worn these down to 20 degrees F and they were plenty warm.
For me, the shoes ran one size small. I wear a 42E in Shimano mountain bike shoes for reference and went with the 43 wide for the Lake and they fit great. If you like to wear really thick winter socks you may consider going another half size.
If you are searching for a winter shoe to keep your feet warm, take a look at the Lake MXZ303-X.