Hi Randy. Definitely the Critter Cage. A corn really isn't going to use the vertical space, except as a baby. In addition, the ExoTerra cage has all kinds of nooks and crannies and I really find it hard to believe one would be safe for a snake, especially a hatchling. I have one, with a gecko in it, so I am familiar with the construction. A 20L will be fine for the lifetime of your corn snake, although the snake would not mind a larger viv as an adult. You can put a baby right into a 20L, as long as you provide deep aspen, lots of hides, toilet paper tubes, vine cover on three sides, etc.