what do you guys recommend in terms of # of rifles, magazines, ammunition?
Start with an AR and a thousand rounds for every shooter in the house, plus an extra AR.
After that, it's all a matter of preference.
Agree that this is a good baseline
NOTE-if you have a fighting rifle (AK, M1, M1A, SKS, etc.) there is no need to buy another one. Just some ammo.
Also, if you have a Sidearm add 500 rounds for that
If you have a HD shotgun-500 rounds
This can be in place of all those ARs
Also, if you have a bolt action rifle in the same caliber as your fighting rifle that is helpful
The point being you may have most of what you need in the gun cabinet.