Is the LAR-8 in stock at some dealer? I don't think they're in full production, and when I tried both calling and emailing RRA I got no response either way.
The LAR-8 and the various AR-10s are good. The DSA FAL is very nice, assuming you meant the SA-58 version (the STG-58 is also nice but not the same). For reliability and overall fun I would get the FAL. For ultimate accuracy I would get some variant of AR-10, whether from RRA, Armalite, DPMS or whoever...
If you want to stock up on mags, the FAL mags are still cheaper than AR-10 type mags, but since the LAR-8 uses FAL mags I guess between those two (and not other AR's) it doesn't matter.