I am a fan of the AR15, and the M1Garand. I have a Tanker Garand.
Here are some random thoughts... With a good 16" AR 15 you can easially have a choice of great optics, making it a valid 500 yard gun, with good ammo of course. It is easy to add lights, they are light weight, easy to shoot/carry, etc. Hold 30 rounds, very quick to reload. Ammo, mags, parts, etc are most every where.
With a Tanker Garand, or a Shuffs Mini G, you have the following advantages. AS a 308 or 30/06, it has a lot more thump, penetration, and wind bucking abiity. But they are very hard to fit optics to.
They only hold 8 rounds, BUT you could have 1000 8 round clips, and thus have 8000 rounds loaded in those clips, or even more.
The Garand is a Classic, fun gun to shoot, and own. I love them...
However IF I could have only ONE for the Bad Days, IT would be a good AR15...
That being said I have many times carried my Tanker Garand, when traveling when going into California to visit friends, or when going on a hunting trip in bear country, as it can double as a spare hunting rifle, where I consider a 223 a "little" light for bear...