I shoot left handed so this is a no brainer for me. I greatly prefer the M1A because I like the traditional rifle ergonomics and the controls are better placed for me. If I shot right handed, I might have given more thought to the FAL, and no doubt, it is a fine rifle. Now that I own an M1A, it's not even a contest. I haven't handled or even looked twice at a FAL since I got my M1A. The M1A has the best sights ever put on a battle rifle, an excellent trigger, is more ambi than the FAL, and tends to be a little bit more accurate. Also, for the sake of history, anyone who says the FAL is more reliable than the M1A is full of it. The US government put that argument to rest when it tested both designs in the early 60s and adopted the M14.
Also, I've cleaned ARs and have to call bullpucky on the first post that stated the AR is easier to clean. No contest. The AR is easier to take apart for cleaning, which is good because you have to do it a lot more. In terms of actual ease of maintence, my M1A is orders of magnitude better than any DGI AR, and that is a fact.
I wouldn't even consider an AR in .308 either. Even a piston one. Better off with a 17S, as suggested--designed from the ground up not to crap where it eats, fully ambi, has a folding stock, actually comes with excellent sights (as opposed to a lot of ARs, which require you to buy sights after spending $2500 on the rifle), and the SCAR is lighter.