FN FAL

If you love it and shoot the barrel out of it, YOU can replace the barrel for $200. You can configure it however you'd like, as a pistol, a 14.5-16 recce style, a longer range setup, it really has no cons. On the other hand, the FAL is a stud. It goes and goes, and is iconic af.

There’s no possible way you want the power and reliability of an FN FAL. It will work too well jam rarely and be boring as hell. Get a PSA AR-10. Jams constantly and stuff falls off of it giving you new projects constantly. Way better.

Think spare parts, parts compatibility, and troubleshooting. If you need help, there are far more people here (I would think) that can diagnose issues with an AR10 than a FAL or G3.

There’s not a lot you can do to modify a FAL without ruining the looks, plus it was really meant for laying down automatic suppressive fire and it isn’t as accurate as other offerings. Same goes for the M1A, yes the SOCOM models are a bit more versatile but you don’t have the ability to adjust the length of pull like an AR-10, which means if you don’t like the LOP or you need to collapse it for compact storage you’re out of luck.

Nothing but love for a nice FAL but ar-10s aren't too expensive if you build or buy the lower and upper separate. And parts are much more prolific.