So if this happened, then I assume it's the apocalypse.
No, just a mental exercise. It could be a fire, a flood, bankruptcy, or any number of things that cause all of your guns to disappear. I know I would do a lot of things different with the benefit of experience.
For me:
-1.
Glock 23 Gen2 Absolute top priority would be getting my carry setup back together, and I could do this easily on day one. (Minus the Adams Holster, so a few month wait with a cheap Galco...) I like the Glock. Simple, soulless, sure... Who cares? It works.
-2.
Marlin 783 .22 Magnum. This would be in (temporary) place of my MSRs. I do not have any pressing need for a thirty round magazine, and the main use of my AR is varmint control anyway, so... This (and all subsequent guns) would be as funds allowed, as I can't imagine all available resources going into the collection.
-3.
Scoped .308 Bolt action These things are just too much fun not to have, and can double as anti-personnel when used as a truck rifle. Probably the Mossberg MVP Patrol.
-4.
SAR-1 AK In case the balloon ever goes up...
-5.
S&W K-frame snub Model 66. The only thing on the list that I would buy as a 'want' rather than a need.
I could really be content with just that.
If I were to buy any more, they would probably be a .22 revolver, and maybe a Remington 870.
What I would do different? A lot... The most radical would probably be that I would have far less handguns than I do now. Sigs, Berettas, BHPs, 1911s, etc. They are nice, but I don't need them. Probably don't even want them, if I'm honest.
The other shocker would be that I would not buy any sort of AR, unless maybe a cheap one as an investment for the next panic. Not to shoot - they just don't do anything for me.
Shotguns? I love my SxS shotguns, but I could do without them. My Benelli, same deal. IF I got a shotgun, it would be a plain, stock, Remington.
PCCs, such as my Berettas? Only if I had money to burn.