The M14 SE does not have the ability to 2 hit unless it's very close against light vesters and any vest shot from the back. So basically the M14 SE is just an AK 47 but a bit better. The CQB has the lowest recoil out of all the guns in the game, most accurate in full auto while scoped(small spread), very decent portability and ROF. The CQB is the gun you should definitely get. or the G36 Valk. even though it's just a re-skin =D
Maybe you should watch some Baxstar's/or any weapon reviewers review on the guns you listed.