No matter how many guns, and ancillary related products you have; you cannot individually use all of your firearms in a defensive, apocalyptic survival scenario at the same time. Therefore I find it beneficial to have pre-selected 1 main rifle, 1 main handgun, and 1 main 12 gauge shotgun for use depending on the specific scenario should the post apocalyptic world become a reality.
When making your weapons selections you want to make sure they are dependable, reliable, robust, and that you are proficient with their use. You may have to become your own gunsmith so having spare parts available and being able to install them are also important considerations.
There is no one right weapons selection for everyone; and everyone has their personal likes and dislikes when it comes to the merits of certain firearms, so it is up to you to do your research when it comes to buying your weapons and obtaining proper training. If a post apocalyptic world does arrive; your survival may well depend on the weapons and training choices you have made.
You can see all 5 of my post apocalyptic fiction books, 2 of my zombie fiction books and 1 of my horror fiction books on the left side of my blog page. Go ahead and purchase one or more over at Amazon.com. They are really quite interesting and entertaining to read if I do say so myself.