Everyone should have at least 1 Mosin Nagant. Surplus ammo is pretty cheap. I know it’s highly debatable, but I love my AK too and the ammo is much cheaper than for that AR.
AR calibers thread that needle between the portability of ammo in the .22 lr range and the power of the AK round.
But... an AR and its ammo cost a lot more than buying a .22 and an SKS, with ammo for each.
The MN is a formidable weapon, and I’ve shot a friend’s unit, but I still prefer my Leupold-scoped AR-10/ 7.62x51 over it.