For home defense/prepper purposes I would go with the AR. It's more versatile in terms of being able to handle I wider range of game size, especially if you invest in a 22lr conversion. Although the regular ammo will still kill small game it may or may not leave much left to use depending on POI, but it can still be done. The ammo will be cheaper when prices return to normal. It's a bit easier to use and more ergonomic for defensive purposes in a wider range of scenarios.
Don't get me wrong. I LOVE a good M1a. But it's larger, more expensive gun and ammo, and thus more restrictive in a larger variety of scenarios.
Once you get your adapter so you can switch out uppers the 901 should be the more practical since you'll have the capability of a multi-caliber rifle. You can keep a .223 (or another caliber AR) upper set up for patrol and mid-range HD, and then your .308 upper as a better long range and hunting option in a SHTF scenario.
I've got extensive range time with both platforms, have owned multiple examples of each, and was just talking about this earlier today. The AR has matured into a great rifle while the M14/M1A is old-school perfection. At the end of the day, shooting the AR makes me feel like a detached, mechanized weapons system handler, or some such. Shooting the M1A makes me feel like a soldier, a patriot, a muddy, sweaty, practitioner of some seldom encountered long-range black magic.
It's got its drawbacks but for pure visceral appeal, I know what my choice would be.
I have a Socom and Standard. They are both highly reliable. As long as you keep them greased up, they are GTG. M1As are nicely piston-driven and nothing sounds better then the pinging sound when firing.