I'd say the M8 is better in SnD and competitives (I GUESS) and AN-94 is better everywhere else. I didn't really put them in the order :S But I would say the FAL is still the best AR and gun in the game.
MTAR (3hit kill range was increased) FAL (semi-auto, auto has too much recoil) AN-94 (start out with select fire if you need to learn how to burst)
MTAR just feels like a wannabe MSMC that needs to have quickdraw, stock, and laser to compete against the MSMC+long barrel.
FAL with select fire is still easier to use overall than the semi-auto FAL, unless of course you have something like the scufs and/or have good trigger finger and the ability to keep high accuracy in all situations, which I've not really seen.
AN-94...is fine without select fire...it's really easy to burst in 2 bullets.
Just started playin so don't have a lot of experience to draw from but I tear through kiddies with the swat red dot with the ergonomic handle thingy. Idk why but I find this game incredibly easy as I only started 2 days ago and I seem to be the best in almost every lobby