I use military packs for my (Austrian Army) and my nephew's (Swedish Army) BoB's.

My DW has a commercially padded backpack and DD2 & BF have small school type backpacks for their BoB's. This pack is not a dedicated BoB which is why I am getting her a 2 person Bob from RedFlare.

DD1 has a very small back pack that holds 3 days of her "special needs" equipment. This pack is inadequate to hold the amount of supplies that she needs. I am getting her a 1 person BoB from RedFlare and I will get her something else for her "special needs" equipment. This second pack will have to fit onto the back of her wheelchair along with her BoB.