I have both and love both. The M1A is almost 2 lbs. heavier, but you get a LOT for that extra heft! Better max effective range, better accuracy, and better barrier penetration being the big ones.
The AK is more like something I would grab to deal with a deadly force situation going down in or around my home, where it is going to be more close quarters, and makes a good "truck gun;" whereas the M1A is my main overall "2nd Amendment purpose" rifle, for dealing with any threat anywhere any time at any range. Plus it makes a pretty damn good hunting rifle. The M1A is a rifle that I am highly familiar with. I am very confident in my ability to make hits with it from point blank out to the limits of its effective range, from field positions, and I know my come-ups cold out to 1000 meters. I have the spare parts to keep her going in the field, and I know how to maintain her. If I could only carry one with me, not knowing what situations I will have to deal with, it would be the old Springfield. So I voted M-14.