I've used an EXO 5500 multicam for an Army ruck since 2017 and loved using it, and got nothing but compliments about it other than the black buckles. Now it just sits in the corner of my office, maybe PM if want to discuss it?
I’ve had a Kifaru Zulu eXtreme Ruck for many years. It was my second Kifaru pack and will probably be the last I ever need. I’m a Kifaru fan but I’m interested in what you find because I need a pack for a teenager pretty soon. Of course he likes the Kuiu Vias pattern…but I won’t buy something just for the color/pattern.
I prefer the EXO frame and EXO shoulder straps. I prefer the Kifaru waist belt. I don't like either the Kifaru or Stone Glacier bags, to me the EXO bags are significantly better laid out. I think all three frames are quite good and really hard to go wrong as long as you buy the correct one for your size and spinal contour. I currently run the Kifaru frame with EXO bags. Buying all three and keeping one is a good idea, confident you'll have a winner out of the three.
I love the way the Stone Glacier frame has the meat shelf built in and you don’t have to depend on the bag for that. I also thing the Stone Glacier frames are the easiest to adjust with the velcro yoke and each shoulder strap being independent. I think the Kifaru frame and modularity allows for more versatility once you get the frame to fit you; their bag and accessory options allow you to do exactly what you need to do. Seek outside has a simplicity about it that makes it appealing, but I didn’t go that route.
I didn’t like the Mystery Ranch frame…it squeaked a lot under weight and wasn’t easy to customize the fit.
My advice is to focus most on getting the frame to fit well and test it under weight. That would require trying multiple frames and being willing to adjust and adjust. After that’s figured out, look at the bag options as all these companies have many routes to go.
I ended up going with a an SG 5900 on a xcurve frame. That’s my main backpacking bag. I added a sherman pocket in blaze from Kifaru and it performs well, also added a bungee cord cargo to allow items to dry and keep my camp shoes out of my bag. I kept my Kifaru frame and have been whitetail hunting and using it for training with the Straight Jacket, which has been awesome.