I'd say it's the anti material rifle the ammo is so dear u think you where shooting caviar and the gauss rifle is easier to get and the ammo is cheaper. i suppose am an anti anti material rifle kinda person.
that gauss rifle is pretty useless if you dont use energy weapons.
i heard the generic sniper rifle is still better but i had enough of that ugly thing in F3, and the AMR is bolt-action
most useless weapon for me anyway is that stupid broken recharger pistol. and i thought the DE in MW2 was bad.
but the worst weapon is probably the rolling pin