M4A1 all the way because it's great for everything it has less recoil then the ACR and the fire rate is higher then every Assault Rifle except the FAD if the M4A1 had anymore damage there would be threads calling it "overpowered".
Used 'em all at one time or another. Retired ACR 6.8 after getting 2500 kills with it, and the G36C after getting +5000 kills and 500 headshots.
Now I stick withe these three -
1) FAD (my favorite of all the ARs)
Keep your powder dry,
AK47 is my favorite AR, followed by the G3Sek-C though I haven't used it this prestige really, and the CM901 which I started using this prestiege.
Ak outraged with Kick and Ex. mags
-Recon (Best Perk ever)
-Hardline (Best combo perk with recon)
-Steady Aim (Its already good with medium-long thanks to kick and I find it alot more useful with it)
G3Sek-C Impact: Ex. mags or Attachments Silenced/RDS (lets be honest it doesn't have the best sights)
-Dead Silence/Sitrep (Sitrep for finding campers then I just wall bang or Dead Silence to creep up on people. Thats right Pika's a creeper)
(You know, going old school )
eh copy and paste on either of those last two classes
You ALL forgot the BEST AR in the game BY MILESSSSSS!!
Deadly from long range, and even deadlier from close range. Stick a red dot and ext mags, with marksman, and steady aim, assassin, and scavenger, burst fire from long range, hipfire from close range, your a moab waiting to happen