The problem with HK91's is that they're pre-ban. There are some decent clones (the SW-3) but wide forearms aren't as easy to come by any more. American part's are also easier to come by for the FAL's.
Mags are down for HK's now too, so that's not an issue.
I prefer the HK91 myself, but the FAL is more tinkerable (though, reliable out of box, tinkering is half the fun :smile:
I don't like the M1a much myself, it's too thick, too unwieldy. The nod for accuracy usually goes to the M1a, but for that price, I can get a great bolt gun.
Also, teh Armalite AR-10. Very nice, doesn't get hot (the HK is hottest, the FAL behind that, haven't shot the M1a) but mag's are expensive.