You have the half clear/half snowy tundra of the mid-to-south, the super rocky west, the hill-y backwoods area of the east and the harsh snowy ice fields of the north.
I always enjoy traveling through the snowy ice fields up north most. Not too sure why; there's just something about the atmosphere I like. I can't stand the western terrain. Cliffs and mountains everywhere you go, at every turn, maks it tough to get to simple places that should be quick to get to. For this very reason, I rarely travel to that side of Skyrim.