You can't really compare a 7.62x39 AK to a .308 FAL. That's like comparing a V6 to a V8.
AK-47 pros.....somewhat inexpensive, rugged/reliable, good intermediate barrier penetration, cheap & plentiful high capacity mags, light weight, reasonably priced ammo, etc.
AK-47 cons....so-so accuracy, limited 300m accuracy/effective range, etc.
FAL pros.......farily good accuracy, good 500-600m accuracy/effective range, great intermediate barrier penetration, cheap & plentiful mags, etc.
Fal cons......overkill power for many applications (especially urban), moderately heavy, moderately expensive, expensive ammo, requires more frequent cleaning/maintenance, etc.
I'm gonna leave it up to you to decide which is better for your specific needs, though there is no one rifle that best suited to all applications.