Can't cut back to just 3 long guns, because I have a vault full of collectable firearms to help diversify my modest investment portfolio in our current time of Biden economic upheaval.
But for everyday use I could get by with 1. A light centerfire rifle for medium sized game, 2. A magnum centerfire for any and all centerfire hunting, in which I still engage, and 3. A good, serviceable O/U skeet and sporting clays gun. I wouldn't need a rimfire as I can do all of my fun plinking and small game hunting with a shotgun or with one of my centerfire rifles reloaded to low pressure, mach-1 to mach-1.5 velocities based on C. E. "Ed" Harris' experience with loading centerfire rifles to mild pressures and velocities using Alliant pistol powders. Nothing quite like rabbit hunting with a light weight, short barreled magnum centerfire!
From the guns that I have owned over the years and have since replaced I would choose the following three:
1. My pre-64 Model 70 Winchester in .257 Roberts, the most accurate rifle I have ever fired.
2. My Remington Model 600 .350 Remington Magnum, which I have picked purely for nostalgic reasons and the fact that it was the one that introduced me to handloading; and:
3. My Browning Citori 12 Gauge skeet gun w/Briley match weight, ultralight, sub gauge tubes.