I do not intend to go through the entire decision making process of how to pick the correct Jump Bag for a particular use - just the basics.
First - Decide beforehand what will be in the Bag - Oxygen only, O2 plus Medical Supplies, O2 plus all Trauma and Medical Supplies, etc.
Second - Organization is the Key. Research the available bags that specifically have the space for the stuff you intend to carry. If the bag does not properly organize the supplies you intend to stock, you might as well buy a wheelbarrow and throw the stuff in.
Third - Narrow down your selection by using any (or all) of these parameters: Price, Color, Manufacturer and Manufacturer's Warranty. The correct bag will fit your budget, be produced by a quality company and backed by said company's warranty policy.
Like any large purchase, sometimes we need help making a decision. Don't be afraid to ask questions about a product. If the Customer Service people know their products, they will be more than happy to help in the selection process.