I'm getting the ARs diamond atm, from what I've used so far I'm a big fan of the MTAR, M27 and Scar. Acog + Stock is my preferred loadout for ARs.
Select Fire Fal is good, better in Core than HC IMO. Not a fan of Select Fire on the SMR though, far too slow. Better off spamming the trigger!
I got them diamond so a lot of work with them all. The Fal nd the SmR are beast if u have a fast trigger finger or with select fire, but not my fav ones. Here's my goto class:
Type 25 w/ silencer, extended mag and stock.
Perk 1 ghost
Perk 2 scan
Perk 3 ( either ) tac mask or eng. (depeneds what score streak I'm using like care package)
Now also the type 25 is the fastest shooting AR too So u can take off the stock and use laser works pretty well. Or use a red dot site. That could help quite abit.
I use to enjoy the type 25, and the swat. But now that I have the m8a1 I never use anything else.
If you put the select fire, target finder and another attacment it seems to work well. For short range I recommend the vector with the long barrel and I like target finder for my site.
Not unlocked the AN 94 or the m8 a1... Or the smr.....or the scar for that matter.
My fav is the Type25 with Stock and Supressor.
I use it with Lightweight perk and it behaves a little like a high powered SMG. It's the only weapon I have gold camo on. The problem is the recoil is a bit erratic because it has quite a high fire rate but one thing that helped for me is trying the Reflex sight.
Close 2nd is M27. I use this as my 'engineer' class with Engineer perk and Black Hat with Scvenger. Usually with a supressor and stock attachment.
Unfortunately the range of both of these ARs is pretty bad. That's why I don't mind using Supressor seeing as the range is the weak point. Try removing the Supressor if you need a bit more range.
If you want an out and out AR with a lower rate of fire but great range and damage (basically a more realistic AR), try the SCAR-H, or the MTAR until you unlock SCAR.