An FNH FNAR, based on the Browning BAR hunting rifle, costs less, is lighter, and more accurate than any M1A, G3, or CETME anywhere near the same ballpark cost-wise. Its 1MOA factory guarantee is beyond any of the aforementioned, as well as AR10s anywhere the ~1000$ price point (yes, a 5000$ Surgeon will be better). I'm not an expert on all AR10s, but I believe most of them in the 1K price set weigh about the same as well (~10lb depending on scope, etc.).
Disadvantages with the FNH are its expensive but well made magazines (price
will come down, but FNH has been slow to respond to Sandy Hook era scarcity, I'm guessing because demand for their other products is still higher). It has a cross-bolt safety which some hate. It has no iron sights, but a long enough rail to mount a reflex or other short optic with back up sights. Being a rifle besting DMR accuracy, I question the need for iron sights, but I know some folks desire them. Unlike an AR10 (but just like the other options) there is a dearth of accessories, though a folding stock has been devised by ACE, and the BAR Shortrak stock can be modified to work for a straight-stock grip. The factory grip is adjustable and more ergonomic than any platform but
maybe the AR and M1A (and only because of owner familiarity)
The gas system is tappet-piston driven short stroke, so very smooth recoil response, and it requires
very intermittent cleaning (~1000rnds). Its disassembly
is fairly complex, but only required every 1000rnds or so. The recoil spring does "sproing" a bit when fired, just like the AR and others. The trigger is not million-dollar awesome, but it is superior to any unmodified service rifle-based platform.
Another really good gun that I'm certain is great in 308 is the FN49. Mine is 30-06 and is extremely nice to shoot (and look at). The Argentine FN49s modified to take 20rnd mags would suit your needs nicely, and they run a little over 1000$ as well (not bad for a nicer-looking FAL made in Belgium)
My FNAR
was my favorite 308; I think it may lose favor to the BM59 I am building. It still needs a lot of work, but it is basically what the M14
should have been all along. The BM59 weighs about 9lb with the huge but effective muzzle comp removed. Probably 8.5 if other unnecessary bits like the bipod and rate-reducer are taken off. Barrel is ~19" and folded is about 2" longer than the receiver. The stock feel is reminiscent of an M1 Carbine Paratrooper (no, I'm not kidding; it feels that handy)
For pure range awesomeness, buy an STGW57 (similar to SIG AMT) kit from APEX, a new receiver shell and 308 barrel, and weld-er up. That would all run ~1200$ if you do the receiver work yourself, and would resell for probably 3X that.
Theres also the MAS49/59 308 conversions, which, if done properly, are very fine rifles and only cost about 500$. If you want a fun range plinker in 308 and don't want to break the bank, this is probably the best deal running, now. Remember to check out the chamber and, if possible, have the gun's reliability tested before purchase (Century screwed up a bunch of guns with worn and wandering reamers when they did their conversions, but many were done by reputable smiths, as well)
TCB