For any BOB (Bug Out Bag), first, just cover the basics and you'll be fine.....and in this order:
WATER (because you'll die quicker without it)
KNOWLEDGE (because with it, you can find everything else)
FOOD (because your thinking is impaired without it)
PROTECTION (because you want to keep the above)
SHELTER (though you can likely find/build it, you'll still want items to help with it).
So, first, WATER.
First and foremost, a straw type filter. Now you can debate brand, etc., but simply put, this gives you safe water from LOTS of sources.
Second, a METAL water bottle. This does two things, allows you to carry the water (and move as rough as you want), and allows you to boil the water (to purify it, or heat it up for dehydrated food).
KNOWLEDGE
You need to know: where you are going, how to get there, and how long it will take. You also need to either have practiced this kind of outdoor trek and living, or at least have researched it enough to feel somewhat confident. Personally, I like to have 2 items for this. One, is a solar power cell phone charger (with flashlight). Second, a cell phone with a lot of memory storage (and even a memory card), and have tons of survival pdfs on it.
FOOD
You want BOB food that is: light, compact, nutritious, easy to prepare (or even needs no prep), and keep a long time. Dehydrated camping/hiking meals are great for this. Granola bars, jerky, etc. are good too.
Second, you want the ability to GET more food. Fishing supplies, also covered next in PROTECTION, things like a gun and/or a knife.
Third, a can opener. Look, while there are plenty of ways to open a can of food, this is by far the easiest, and it's a pretty cheap and easy piece of gear to have.
Finally, ways to make fire. No need to be all primitive here. A lighter is a good thing. But, doesn't hurt to have storm matches and/or a flint striker too. May want to have some kind of small pan to cook in, or at least an extendable camping fork, to hold the food over the fire.
PROTECTION
This is all a matter of preference, but I personally prefer a nice .22 pistol because you can carry a TON of ammo, and it's good for hunting small game (I'd much rather have to eat a small rodent then figure out how to gut and preserve a deer, while bugging out, lol). Plus, if you shoot at someone, they really don't care what caliber is coming their way, they will take cover. (and you'll outlast them in the firefight).
A good fixed blade knife (full tang, meaning blade extends all through the handle) is also good not just for defense and hunting, but also just for having as a tool.
SHELTER
This really depends on your climate (and the season). Bugging out in the FL summer is different than winter in MI. Basically, you want something that is waterproof, will keep the wind off you, is compact, and easy to set up/take down. Personally, I like the little dome tents. I've had these stay up in storms that tore fancy tents to shreds. But, you can likely always find some abandoned building, sewer pipe, overpass, big tree, etc. so this is why it's last on the list.
Anything else, is just gravy....comfort items, tools, etc. I find it best to START with the basics, then go from there. I don't want to be loaded up like a Sherpa on Everest. If you cover the basics above, you'll be fine.