Just wanted to give my input on the two. I have about 16 hours on my profile at the time I'm writing this, with hundreds of hours in CoD, Battlefield, and many other FPS games.

This debate entirely comes down to how you personally play the game, how aggressive you are, and also your personal skill level.

The AKM is much better at prolonged gunfights, and is much more forgiving if you miss shots. You don't need to play nearly as safe as you might the FCAR, and this allows much more freedom to make mistakes. However, the AKM is less reliable as scoring kills at medium range. You'll most likely end up with a ton of assists if you're not playing highly agressive CQB. This isn't necessarily a bad thing.

The FCAR on the other hand does 60 more DPS, but is much less forgiving when you miss shots. However, in an even one on one fight with nearly any other gun in the game, the FCAR will win. The caveat is you need to make much more of an effort to keep people somewhere in the medium range area. Reloads are quicker than the AKM, so in a one on one fight you'll win only if you have cover, and can control the fight. The FCAR is also much more reliable with the sight for hitting shots but also for securing kills. Enemies have much less time to react to you and you can secure kills easier, which is usually better than going for assisting damage. FCAR is also more reliable at damaging through heals, for those pesky H M situations.

I would consider the FCAR a burst style weapon while the AKM is an endurance weapon.

Are you maybe not the best player, you aren't the best at tactical positioning or playing against multiple enemies at once? The AKM will be much easier to use.

But if you're a better player who is great with movement and escaping and is great at positioning, the FCAR will be a much better weapon to use.