AK-74 or M4A4 or M4A1-S??

AK47 for sure as a main weapon.
But when you need to choose your loadout between m4a4 and m4a1s i'd go with a1s. You have more choices, they added 25 bullets instead of 20 so it was buffed. the precision is 10 times more accurate and you can control the spray a lot easier!