I've never used bunny boots. I have two pairs of Sorel pack boots, one pair has leather uppers, and the other pair has cordura uppers. Pack boots are good if you aren't walking long distances. I picked up a pair of mounataineering boots this fall, and they are much better for hiking in, and crampon compatable.
It really depends on what you are doing. If you want to keep your feet tosty in a cold stand or blind, get pack boots. If you want to travel any distance, get some mountaineering boots and gaiters.
