I've gone through most of the 308 "battle rifles" available in the US at one point or another...M1A, PTR91/G3, FN SCAR, FN FALs (lots of those), AR10...I'm sure there's a few that I've forgotten about
If I had to pick up and bail for whatever reason, the SCAR would be coming with - about the only thing I haven't done to it is SBRed it and put on a short barrel...the 16" looks kind of wonky on it, but it works. It's light, low recoil for the caliber, nice long top rail, ergonomics are fine, etc. Downside is it's not super suppressor-friendly for civvies (FN will disavow the gun if it thinks you've shot it suppressed and damaged it); there's some aftermarket gas plugs to deal with it and you can replace gas jets in it to adjust how it acts yourself, but it's not intuitive. Front rail space is a bit limited on the right/left/bottom. There's aftermarket rail sections that bolt onto the front of the rifle for things like lasers and lights...one of these days I should pick one of those up. The rails on the main body are also cheese graters, though I think you can replace them now with M-LOK sections from some vendors...again, I should probably actually look into that. In the mean time I'm running PMM rail delete panels instead. Much more svelte.
My FALs are fine and great and would probably be a 3rd. Like the M1A or G3/HK91/PTR91 clones though, they suck for mounting optics on. Easier to clean than the G3/HK91 clones though, as well as the M1A, or AR10.
The AR10s are pretty ergonomically familiar to everyone...I have a pre-built Aero M5E1 18" upper (the E1 in a nutshell moves the handguard mounting interface off of the barrel nut, and onto the upper itself - true free-floating...how important/better it is than having a handguard on the barrel nut is probably incrementally better if at all, but *shrug*) that seems to do ok with factory 308 both accuracy and precision wise. It's got a Rubber City Armory AR308 BCG in it, I removed the factory gas block and installed an adjustable one for shooting suppressed, built a lower out with a LaRue Trigger and most of an Aero parts kit, a fixed A2 stock, etc. So far mine has been %100 reliable though I haven't really had a chance to tune the gas block for both suppressed and unsuppressed fire yet. Probably a grand or so into it, before optics and muzzle devices.
The downside to an AR10...there's at least 3 different competing standards for any one part. If you build your own, you need to make sure you have the right receiver extension, buffer, bolt, bolt carrier, barrel, upper receiver, lower receiver, gas block, gas tube, barrel nut, barrel, magazine...even the small parts can differ depending on the pattern. If you buy a pre-built it'll be a lot easier...but only if you never touch it. The Sig 716 for example is a great rifle; by all accounts it's fantastic. UNTIL you decide you want to change parts on it, or put on an adjustable gas block, for example. Sig went their own way with a lot of parts so there's not a whole lot of commonality between their product and anything else on the market. If you never want to change anything about it and can live with how it functions out of the box with a can on it (if it functions at all), then great, you're all set. Otherwise...well, good luck
If you want to buy one that can do everything? My vote would be a SCAR, or an AR10. The AR10 may be a little trickier but it's infinitely customizable if you have the time/money or are looking for something that can do anything, or hyper-specialize into doing only one thing but doing it really well. The SCAR's strength is that it can do everything reasonably well...but there's not a whole lot of customization past that; you're not turning one into something super accurate, for example. It's just not in it's DNA.
Edit - I wouldn't bother with an M1A unless you don't like money; it does nothing well. I'd take an HK91 over that, or a FAL, any day. The HK91 can be had for a grand or less and mags are dirt cheap; they shoot really well and can be reasonably battle rifle accurate. They suck for mounting glass on, but they're historically really reliable and frankly pretty fun to shoot. FALs are great, but mags are getting expensive and the days of $99 kits and $300 builds at a gunsmith are long gone. Good luck getting into one for less than 2 grand (it's technically possible, I guess, but not likely) and DSA has been known to have some parts issues with their domestically produced guns; breakages, etc. They're also not going to be glassed easily. The adjustable gas system is ok, but it's pretty much set it and forget it...you're not going to do a whole lot of tuning with it. The HK91 and FAL are also not really super friendly to suppress if that's your thing as well. They (DSA) do make suppressor gas plugs for FALs, but..I took the muzzle device off of one of my FALs to see if I could suppress it and the (factory surplus) bore was off-centered enough to make it a no-go for putting a can on. Oh well.