Sorry but fail.
One of the best all rounders, the SCAR what is it, level 5 unlock, piss easy, M4A1 is before the scar too, also a very good all-rounder, the famas isn't a bad gun either if you get used to burst fire and it makes you learn to be accurate because you can't spray with it as easily as an automatic.
Marathon, stopping power, commando/steady aim, all unlocked at very low ranks, you can't use guns and perks as an excuse.
The best players can own with any gun/perk combo
I prestiged the other day myself and actually found myself doing better because i wasn't f**king about with shotguns all the time (although i'm not packing the AA-12 again)