The best warzone loadout?

Here you go, depends on your preference of gun but the first one is for starting off and from there depends on what you like to shoot with LMG, AR, Sniper, etc. :

Starting off I recommend using the following loadout:
Kilo loadout
Attachments: Monolithic Suppressor, Singuard Arms 19.8" Prowler, VLK 3x Optic, Commando Foregrip, 60 Rnd Mags
Secondary gun:XM4
Attachments: Suppressor, 13.5" Task Force, Tiger Team Spotlight, Raider Pad, 45 Rnd

MG82 loadout
Attachments: Suppressor, 16.4" Task Force (or Field Agent Grip for better ADS), Axial Arms 3x (or Tiger Team Spotlight if secondary), Fast, Mag GRU elastic Wrap

SNIPER:
Kar98k Loadout
Attachments: Monolithic Suppressor, Singuard Custom 27.6", Tac Laser, Sniper Scope, STVOL Precision Comb (or FTAC Sport Comb)

AR:
AK-47 Loadout
Attachments: Suppressor 20" Spetsnaz RPK Barrel Tiger Team Spotlight KGB Skeletal Stock 45 Rnd

SECONDARY:
Mac-10 Loadout
Attachments: Agency Suppressor 5.9" Task Force SOF Target Designator Raider Stock STANAG 53 Rnd Drum

Another AR:
AMAX Loadout
Attachments:Monolithic Suppressor XRK Zodiac S440 Commando Foregrip VLK 3x Optic 45 Round Mags

Just my personal favorites that I have used.