It's funny you would suggest this tread. I',m older now and have owned more than 100 different guns in my life. Each purchase I have made for myself, usually has been accompanied by 2-3mos. of research and comparison of differing manufacturers offerings and talking to people who already own what I'm looking at. Then I decide if it is worth getting for ME. Now I have given most of what was my "collection" to my children (although my oldest daughter is holding out for my Kimber CDP II .45), I have focused on the following:
.22 semi & bolt action rifle & .22 semi & revolver why? Ammo easy to get and stock away and I don't care what anyone says they can be quite deadly (years in LE taught me that lesson many time over).
9mm pistol & semi rifle why? most common NATO round if it ever gets truly ugly you'd probably be able to find this stuff (ammo) laying around.
.45 pistol why? proven performer & ammo is fairly common. It makes bad people say ow, if they still can and others think twice.
.223/5.56 why? no comment required although, AK47 does get honorable mention in this category
12 & 20ga's why? Common Ammo and some women don't like 12's and despite what some will argue, these are about the only thing that can truly slow a charging body, notice I did not say kill or stop (instantaneous requires an RPG). In real life that's important and forget what they show you in the movies.
My keep list is reduced to 20 various forms of these weapons, and at this point in my life I find them to be most satisfying. Good luck and enjoyment to all of you on your individual journeys of ownership, I have found this process to highly personal (don't feel like you ever have to justify yourself if you did your research and you bought well meeting your need).
