I have had a K2, K3 and now the K4. My hunting partner has several Kifaru packs and has had SG too. I am a big fan of the EXO stuff, it fits me better. I have hauled heavy loads with the others too, and still for me the EXO was the best. To me packs are like boots, they fit everyone a little different and something that works for one guy might not work for the other. Kifaru has a ton of options for bags and organization but that can come at a price, both financially and in the way of paralysis by analysis trying to figure out the best kit, but it gives you the options of changing things up for the specific "mission"