the Ultraday is a nice pack. It lacks pockets which can get annoying in the whitetail woods if you carry a bunch of stuff (calls, gloves, back up release, food, scents). It gets cluttered really quick.
The Superday is bigger but has somewhat of the same issue.
The Monster was one of the nicer day packs I ever used in the whitetail woods. But, it just didnt have the room for packing extra clothes. One advantage was with less room...you take less useless crap in the woods.
The Whitetail Hybrid pack has been the best option for me so far. It has a few to many useless pockets but all in all...it does very well for what I use it for. Room for extra clothes, pockets for all types of crap, and it stays somewhat organized.
hope this helps