Reasons for a FAL:
A Fal (unlike some other 7.62 MBR's):
Has cheap mags. You can get them for $4. (Unlike a M1A1 or an AR-10)
Has a charging handle on the LEFT so you can maintain a firing grip during mag changes (unlike an M1A1)
Has a charging handle placed for easy access (Unlike a HK91)
Has a bolt hold open that activates after your last shot (Unlike an HK91)
Is ergonomically friendly
Does not shit where it eats (unlike an AR-10)
Is not front heavy (like an HK91)
Is very easy to clean (easier than every other platform I have tried)
Is easy to take down
Is available with a forward assist (I have two with this feature)
Is available with real sights (Check out DSA's Para sight. It takes an AR15 aperture)
Has an adjustable gas system for different loads (I love this feature)
Parts are cheap
Furniture is cheap
Barrels are cheap
Actually works well in a shorter package (I have two)
Will feed anything
Recoil is very mild (unlike my HK91)
Is the most reliable weapon system I have ever used
Has been used in 90+ countries around the globe...
ETC.
Do not accept second best. Do it right the first time.