If you could only have one gun as your do all gun, which gun would you pick /k/? Also, how would you set it up? I am going for a single gun setup, but if I truly need more than one feel free to list it.

Do all as in meaning:
>Hunting
>Self-defense
>Anything I forgot to include
>Like a SHTF gun

How would you set it up as in meaning:
>Red dot sight (example: Aimpoint, Trijicon, or cheaper like Holosun)
>Holographic sight (example: EOTECH)
>Iron sights as backup if the main sight fails or iron sights over everything
>Stainless, cerakote (or is there something better as a coating)?
>Anything I forgot to include (better optics I don't know about, etc.)

Everywhere I see:
>Random types of AR-15's
>Glock 9mm pistols

Are they really that good for every scenario? I am trying to decide on a SHTF type gun and I am curious what /k/ would do. Thanks in advance to anyone who replies.