I've owned a heck of a lot of guns over the last many decades and many I have sold or traded and didn't miss one bit. But several guns I have gotten rid of and later figured out that I absolutely must get another one like it. After all these years I have come to the conclusion that I will never again be without a 1911 .45 acp. The same goes for a 4" M-19 .357 magnum and a quality 20 gauge SxS shotgun, and a small .380 auto Kel Tec or Ruger LCP will also be around to slip in a pocket. These may not be the most practical, or best "all around" guns they are just the ones that meet my needs and I enjoy owning and shooting.
I'm kind of surprised there are not a lot more "must have" guns on the list, and I would give an honorable mention to a Ruger 10-22, Remington 870 shotgun, and a S&W airweight J-frame, but I don't feel as strongly as these as the above mentioned guns.
I'm kind of surprised there are not a lot more "must have" guns on the list, and I would give an honorable mention to a Ruger 10-22, Remington 870 shotgun, and a S&W airweight J-frame, but I don't feel as strongly as these as the above mentioned guns.