Winter sleeping bag (-25 rating)

Hi All,

Im looking to buy a sleeping bag in the -25 range.

I will use it in a floorless tent, sometimes more then 3 days in a row.

Would I be better with a waterproof shell or only water resistant ?

Which, of the two bags below, would you choose and why ?

If you know any other bag that would work, I would appreciate suggestions.

Western Mountaineering Puma MF
-25
3 lbs. 7 oz
MicroLite XP™ Shell (Water Resistant)

Feathered Friends Ptarmigan
-25
3lb 15oz
Event Shell