Which has less recoil the FAL, the M-14, or AR derivatives in .308?
Well, I don't currently own a 7.62 NATO AR, but I have fired one.
Recoil is subjective.
IMHO, they all recoil about the same, assuming that the FAL has had its gas system properly adjusted.
AR-10 is fairly benign in recoil, however, the AR-10 I fired had a muzzle brake that mad the blast & noise very fierce.
FAL-Recoil is generally mild if gas is properly adjusted. IF the gas is not properly adjusted, it can be a bit more stout; on par with a 7.62 NATO bolt gun. Also, some FAL stocks fit different than others. Some individuals will experience cheek slap with either straight FAL or humpback FAL stocks. I don't have that issue.
M14/M1A-Typically, these don't recoil too badly. Most will feel like an M1 Garand in recoil. Wood stocks tend to be heavier and dampen recoil slightly better than the synthetic. Short M1A's like the Bush Rifles and SOCOM have a fierce blast/noise issue that may cause a flinch.
G3/CETME-These have the reputation of being "heavy recoiling". I haven't necessarily found this to be the case. Yes, if the gun has a bolt gap that is approaching minimum specs, it does "kick" more. Yes, the G3 is unpleasant to fire witht he telescoping steel stock. But in most instances, the recoil is no greater than any other 7.62 NATO rifle.
Again, they're all sort of the same. Some are louder and have more muzzle blast, but that's a function of barrel length and muzzle device.
If you can handle one, you should be able to handle all, but again, recoil is subjective and shaped by many factors including how the stock of a particular gun "fits" you.