I had the Guardian for a long time, and it was my favorite backpack whether I was transporting a fight stick or not. It was massive, could carry a lot, while never feeling uncomfortable to carry due to how much surface space was resting on your back. The main issue I had with it was that it felt like a large floppy backpack that didn't protect the cable to my Hitbox (it has the cable just poking out, unprotected, pretty bad design flaw).
I decided to pick up the Aegis, and while I like the aesthetic look of the Guardian more, the Aegis has kind of ruined my use of the Guardian for transporting fight sticks. The laptop pouch is incredibly useful, and I can still fit loads of stuff in my Aegis, with pouches to organize stuff a lot better. At one point, I had my Switch, Hitbox, PS4, laptop and all the necessary components for all of them (controllers, cables, etc.) in this backpack, and it never felt like I had to squeeze them in. On top of that, the backpack was heavy, but in no way uncomfortable (again, due to the large surface area resting on my back). On top of that, the extra padding on the Aegis made it even more comfortable than the Guardian was in the same scenario. I'd highly recommend the Aegis to anyone whether they transport fight sticks around often, or not at all. It's just super convenient to have a large backpack where you don't have to think "do I have room?". Fantastic product, and I'm sure this will be my new favorite backpack until Qanba releases a new one.