For me, at this point in time, it would have to be my 5.56X45 in a CQB carbine and my H&K 91 in .308 for social purposes. Both topped with iron sights and an Eotech 512. For hunting, it would be my model 70 Clasic Mtn rifle in 280 Rem and my Model 700 in 35 Whelen.
It goes without saying that we get to keep at least 2 rim fires as well. I'd keep my little Anshutz bolt gun, my 1022 Camo, a Marlin 60 and Ruger New Model, and the old Ruger Standard, the MK I, the Marlin 22 mag, etc, etc...and we didn't mention centerfire handguns or front stuffers.