OK, I'll play.
First off, I don't think my life will change all that much in the next 20 years so I will use the last 40 years as as to what firearms I have used and need.
#1 would be my deer/elk rifle. I have more expensive,exotic or rarer rifles then this plain Jane Mark X Mauser, but it fits me, has iron sights and is chambered in the .30-06, which if you are a reloader makes it pretty versatile.
#2 is my Winchester 52. It probably would be better to pick a 10-22 or a marlin 39, but I like the weight and accuracy of this one.
#3 My LC Smith 16 gauge field grade. I hunt mostly upland game and this has been my go to shotgun for the last 10 years.
#4 1911 Commander. 45 ACP. Can't think of a better CCW for me.
#5 Smith and Wesson outdoorsman. Maybe it would be better to pick a Ruger semi auto or my Model 18, but I like the weight and the sight radius plus I shoot it well.
#6 The last one is the hardest. Perhaps I would be better served by picking an AR15 or Ruger Mini 14 or a MI carbine in case the zombies come over the hill, but it hasn't happened yet and I carry and shoot this Colt New Frontier a lot. So it is my last choice.
This is just a fun exercise. I do not condone or advocate the limiting of the number of firearms one should be able to own.