All depends on what your particular situation requires and needs.

The short answer:

Rural/suburban - 556/762 pistol with a folding pistol brace
Urban - 556/300 pistol with a folding brace

No need for a 9mm AR build as you should already have a pistol on you.

1 mag in at all times, cruiser safe, three mags backup. Sling

Never leave a gun in a car, always take it with you. So backpack is a good idea, or lock into your car/truck somehow.

Med kit is a must

There's a lot more.

I could write a book