I have many layers of planning in place (as should you). Not one "kit" or "strategy" fits every situation or circumstance. I have developed an overlapping plan which includes various "kits".
I approached every kit the same way...
1) Evaluate my needs;
2) Evaluate my environment;
3) Develop a strategy;
4) Develop a kit to help implement the strategy.
Everyone wants to jump from "I need to plan" to "build a kit" which is actually fine, because unless you live or travel in an "extreme" environment all of our needs are basically the same...
1) Tools = gun, spare mag(s), knife(s), basic gun maintenance kit, knife sharpener
2) Fire = 2x lighter, ferro, tinder
3) Water = stainless bottle, purification tablets, filter
4) Shelter = poncho, trash/contractor bag, space blanket, wool (hat, socks and gloves)
5) Cordage = 325 and 550
6) First Aid = CAT, QuikClot, moleskin, antiseptic, duct tape, sterile dressings
7) Navigation = LED flashlight with extra battery(s), compass
8) Food = prepackaged emergency ration, 22 firearm and ammo, fishing kit, snare kit
If you still have room in your kit add...
8) Luxury = polypro under clothes, gore-tex rain gear, improved shelter (to possibly include a gore-tex bivy bag and insulated blanket), more wool socks, mess kit, titanium utensil, additional flashlight batteries, additional food rations, expanded fishing kit.
Restated my concerns in EVERY environment (city to country) from a small black out to a full scale break down or invasion is....
#1 = Personal Defense
#2 = Exposure
#3 = Dehydration
#4 = Injury
#5 = Escape & Evasion / Travel
#6 = Nutrition
Since we can't carry a GHB, BOB, INCH around every day you have to prioritize your needs and start with the largest kit you can COMFORTABLY CARRY EVERYWHERE and build increasingly larger kits. For me this means...
EDC = knife, gun, spare mag, lighter, flashlight
Briefcase Kit = bigger knife, knife sharpener, lighter, space blanket, compass, suck-thru survival straw, water purification tablets, 325 cordage, small stainless tin, etc.
GHB = knife(s), basic gun maintenance kit, knife sharpener, 2x lighter, ferro, tinder, stainless water bottle, purification tablets, water filter, poncho, trash/contractor bag, space blanket, wool (hat, socks and gloves), 325 and 550 cord, CAT, QuikClot, moleskin, antiseptic, duct tape, sterile dressings, LED flashlight with extra battery(s), compass, prepackaged emergency ration, 22 firearm and ammo, fishing kit, snare kit.