That's a hard question but I'm going to have to agree with what you said. Mine would be a Marlin 39 .22lr, Remington 870 12 gauge, and some sort of bolt action 308 or 30-06.
As far as the AR caliber goes, it all depends on what it will be used for. .223/5.56 is cheap for target shooting, and its a good varmint round. 308 is a good big game cartridge but its going to be more expensive. Then theres the 450 Bushmaster and 50 Beowulf if you like big bore stopping power. 6.5 Grendel and 6.8 SPC are good all around cartridges. Of course you could buy an AR in .223/5.56 for cheap shooting and varmints then get a 6.5, 6.8, 450 or 50 upper for big game. A 308 upper needs a different lower receiver due to the cartridge length.
As far as the AR caliber goes, it all depends on what it will be used for. .223/5.56 is cheap for target shooting, and its a good varmint round. 308 is a good big game cartridge but its going to be more expensive. Then theres the 450 Bushmaster and 50 Beowulf if you like big bore stopping power. 6.5 Grendel and 6.8 SPC are good all around cartridges. Of course you could buy an AR in .223/5.56 for cheap shooting and varmints then get a 6.5, 6.8, 450 or 50 upper for big game. A 308 upper needs a different lower receiver due to the cartridge length.