RE: which would you pick
Looks like apples to oranges to me.[8D] Hard to tell anything for sure just looking at the pictures. The Spot-n-Stalk is small, doesn't carry the bow and only a few extra items. It also looks like the quiver would get in the way when walking. You would also have to have a quiver that locks the arrows in (like the one shown) so as to not loose your arrows. This would also slow down your time for a second shot. The spec states that it is "hydration ready" but I don't see where it would go.
The Spike is bigger but it doesn't have any pockets up front for you rangefinder so you will have to have a vest or something with pockets underneath. It has a pocket for a hydration pack built in. It will also carry more stuff because it is bigger. My problem is I would be hotter (back would sweat) with it on my back. You would have to keep your quiver on the bow with this pack.
I think the packs are in two different leagues so it will come down to what you want in a pack.
Happy Picking
Reid