Same as I did before; first rifle would be military, because I think that since we are all members of the unorganized militia ( by law in the USA), that is my responsibility - same as the Swiss. I had two centerfires in my teens, but when I turned 22 and had the money, I bought a Springfield M1A. Then an FAL, then two HK-91s. So it would be another M1A if I had the money, or an AR-15A2, if on a tighter budget, but both ASAP.
But in sporting rifles, I would find an older Remington 700 just like my one from my teens, in .30-06, or a new Winchester M70 Featherweight in .308 Win.
Marlin 39A .22 LR.
Benelli 12-gauge autoloading shotgun.