Of all commercial medical kits, I think Wilderness Medical Systems’ Humbug II medical kit is the best for survival purposes. The pack isn’t too big but is big enough for a family of four to survive at least a week without a rescue, of course given that they have all other essentials they needed as well. The pack was designed for campers in remote nations such as Tajikistan and Kyrgyzstan, which are very sparsely populated.
A good and somewhat affordable medical kit to put in a ready pack is the Adventure Medical Kits Mountain Pack Comprehensive. This Kit can sustain a family of four for at least forty-eight hours before help arrives, dealing with nausea, dehydration, cuts and scrapes, CPR, and even bone fractures. The Mountain Pack Comprehensive is also a medium size and lightweight, as well as being waterproof.