For me, the difference between an AR style 308 and an M1A comes down to weight and style. If light weight is important, then the AR is the better solution. If weight doesn't matter and you prefer steel then go with the M1A.
Personally, I like the M1A, but if I had to carry it for any distance, I'd probably toss it for the (uglier IMHO) AR10 style rifle.
FWIW, the aesthetics, look and feel of a gun DOES matter to me quite a bit, unless you catch me after I'm sick and tired of lugging it around.