I do NOT agree that Kifaru, SG and EXO are the top three of packs, and I currently use an older Bozo-made Dana Terraframe, I have modded to haul meat and emerg. gear. My main packs are now SO Divide MC fully rigged and the new SO Exposure 5000.
I have carried a LOT of packs in 61 years of hiking, 53 years of hunting and while working for the BC and Alberta resource depts. I have not used an EXO or an SG, but, had two Kifarus, 1st. gen. and could not make them work as well as the several MRs I had......FIT, comes first and some designs work better for some body types than do others.
So, I would examine as many of the high end packs as you can, then, pick the one which is most comfy FOR YOU. I like SO as they are SO light, simple in design and nothing has ever been quite as comfortable for me. All of the top end makers will give stellar service and all of them make gear that we could not even dream of when I was young.
Call the various guys and discuss your needs, then consider the advice you get and go from there. If, I were younger and richer, I would try an EXO, new model Kifaru and an SG, lots of fun and they hold their value in the "pre-owned" market.
HTH-JMHO.