Re: M1A vs. AR10 7.62 NATO platform?
First off, I love both the AR-10 platform rifles and the M1A (I own both and shoot both frequently). That said, my AR-10's are my preferred 7.62/308 semi-auto rifles (and add my POF P-308 to the AR-10 type rifle list).
In terms of inherent accuracy, I think that the AR-10 platform rifles have the advantage. You can take a rack-grade Armalite AR-10 rifle and with quality ammo/shooter, get below 1.5MOA out of the box. You'll be sub-MOA with some of the other factory offerings such as the AR-10(T) rifles/carbines and SASS rifles. That is not to say that you can't make an M1A shoot well into the sub-MOA accuracy range...but it'll cost you handsomely compared to the costs, etc. of an AR-10!!
You also tend to have more flexibility with the AR-10 platform in terms of upgradability. If you need to fill a different role, say long-range precision rifle to a close-range defensive carbine, you can swap out an upper in a matter of seconds. I do this with one of my AR-10 rifles that I have setup with a long-range upper, 24" barrel, 20x optics and a second 16" carbine upper with irons, an EoTech/Magnifier, etc. for short-range work. I keep these together in a single hard case and can cover the range from CQB to 1k with one lower and 2 uppers.
In terms of reliability, that is a tough call. My AR-10 rifles are extremely reliable, but I have on occasion had a FTE/FTF...likely my own fault and not the rifle's. I can't think of a single, non-operator error related malfunction with my M1A or any other M1As I have owned. They just run!!
As far as specific rifles/mfgs/etc., there are a $H!TLOAD of options floating around depending on your specific needs/wants in a rifle. If you have something in mind, post it up and I am sure the membership here can point you in the best direction.