Get a Acog'd ak47 as your primary and a g36/l85 (any variant)/scar/any other gun you like as a secondary
I've come to like the l85 (i didnt buy the perm, i lucked out on a case)
AK47's are accurate as hell and in close quarters you can fire off the 2-3 kill shots while scoped very quickly (tap the mouse button or burst 2 shots at a time)