We arrive at the first and really only CoD that I can actually comment on. The name of the game here is ARs. While I think traditionally CoD tries to make SMGs good at close range and ARs good at medium range, in BO1 ARs are just good at basically every range, including extremely long range. There's just no damage fall off and their TOK is about on par with SMGs if not faster. To that end, common weapons included the Galil, AUG, AK-47 &, Commando. If you wanted to run an SMG, the MP5K with rapid fire was the way to go though the AK-74u was an alright alternative. The Stoner LMG was an alright choice as well, as were the L96A1 and PSG1 Snipers, usually with Variable Zoom. The king of them all however was the Famas, an AR that honestly had more in common with SMGs. Super high ROF, incredible range, and unlocked super early in progression. Secondaries weren't really worth a damn, the CZ75 were probably your best bet for pistols but I'd sooner recommend just bringing a Strela to shoot down killstreaks.
For the remaining equipment, Frags, Flashs or Concussions, and either Claymores or Motion Sensors were your go to options. Perk balance was all over the place and largely depended on how you wanted to play: for run and gun style, you'd rock Ghost with a suppressor while camping playstyles preferred Flak Jacket with grenade launchers. The best perk 2, far and away, was Slight of Hand. Perk 3 was actually decently balanced overall though Ninja and Tac Mask were the most common choices. Killstreaks were all over the place as well and often depended on your playstyle: you could go all intel with things like the Spy Plane and SR-71 or more offensive with the Chopper Gunner and Attack Helicopter. Generally, due to how common Ghost was, you'd opt for streaks that could counter it.