Perks are extremely dependent on style of play, so it's different to recommend a specific set to choose. That said, there are a couple that really jump off the screen at first look.
Wildcards are essentially just "super perks" that add polish to one's loadout. Mods Beast Law Breaker and Perk Greed are particularly enticing — the ability they provide to add multiple Slot 3 perks offers a huge boost. Combining Ghost with either Cold Blooded or Ninja from Slot 3, for example, will probably reduce deaths by an average of at least a couple per game.
AUG
The AUG absolutely beams enemies right now with consistent one-burst efficiency. When used properly, it puts opponents to sleep quicker than almost any other Black Ops Cold War weapon outside of point-blank range scenarios.
Keep in mind, though, that only people who have reliable aim will find the AUG to be an elite weapon. One missed burst in a direct confrontation and it'll be difficult to recover to get a kill.
MP5
Here's the likely favorite multiplayer weapon out of the gate. It checks the boxes of a popular, borderline overpowered SMG: Unlocked early, lightweight and dominant in the types of one-on-one exchanges encouraged by the game's map layout.
If you can't beat the wave of MP5s, you may have to join it soon.
M16
The M16 is strong in the same way the AUG is strong in Black Ops Cold War — it's a reliable one-burst killer even at some distance and doesn't have excessive recoil. The AUG might have a slight edge over the M16, but it's really close.
AK-47
Amid maps that at launch are skewed toward up-close confrontations, the AK-47 might be the best assault rifle available for those hungry to thump the barrage of SMG users in mid- to long-range clashes. It's solid across the board and feels comfortable at all ranges in the way any great assault rifle should.
The AK-47's iron sights are also far less clunky than the iron sights on some of the other top weapons, which provides the option to forgo a sight attachment in favor of other advantages. This is as classic of a gun as it gets, and about as viable as the rifle has been in a Call of Duty game for a while.
XM4
The M4 is another weapon that has been a go-to across generations of Call of Duty. It's not the beast it was in Modern Warfare, but it still feels very solid in Black Ops Cold War as an alternative to the AK-47. Attachments such as the Airborne Elastic Wrap and the 13.5'' Task Force barrel really make the M4 play up from its base build.
AK-74U
The AK-74U represents a nice in between weapon that offers some of the draws of assault rifles and SMGs. It's probably going to be the second most popular gun in its class for the foreseeable future behind the MP5, but balancing adjustment updates from Treyarch could change the dynamic there