Seems most people prefer a small knife for hunting. I've used all sizes, and find it much more comfortable and natural to use a 4"-5" bladed knife, with less belly in the profile. Of course, I'm just field dressing, and skinning is a different matter, both in size and blade shape.
Like Dwayne said, when large and medium knives are paired, weight can be an issue. So, if I were to piggyback two blades, and both were Busse or kin, I think the ultimate combo may be a Basic 9 or Battle Rat with either a Bog Dog/Dog Skinner, S5, SS4, HRLM, or RMD. That would be a rig you can wear all day without hitching your pants up all the time, and there's pretty much nothing it can't handle.