Which chaos god has the strongest army in lore?

[Puppet Pal Clem]

What would be a consistent nightmare to fight and how would you rank them in order from hardest to easiest.

For elfs, dwarves, and humans to fight.

[TheSilverRaven]

The power of the chaos gods wax and wane and who is strongest at any given time is subject to change.

Typically it goes Khorne strongest, then Tzeentch, then Nurgle, and Slaanesh weakest. But again, it varies. During the End Times (sh*t as it is), for example, Nurgle had overtaken the others and was the most powerful.

As for armies, well all of them have a theoretically infinite number of daemons at their disposal, so if they were able to manifest all of that, it doesn't really matter.

[Mania]

As Khorne places his focus on warfare, his Daemons are naturally superior in that field. Nurgle Daemons are more for spreading disease, Slaaneshi for y’know what, and Tzeentch in magic. Of course, all three of their specialties can be applied on the battlefield, but in direct confrontation, Khorne Daemons usually come out on top.

Humans can’t counter disease, seduction, and magic as well as they can a Bloodthirster sword. Dwarfs are almost entirely immune to the first 3, and Elves, well, they’re decent against magic.

[Zeek]

There's not really a set-in-stone ranking order of power, as like the person above said they wax and wane all the time.

In terms of which is the "worst" to fight? That's a tough one.

Khorne dudes are said to be exceptionally brutal in melee combat and shun ranged combat pretty much entirely, so as an elf or human with access to bows and guns, this pretty easily takes Khorne out of the running assuming you see them coming before they reach you. If they get to you, you're boned though.

Slaanesh is fast and can render you helpless as they play off your fears and desires. You would need titanium fortitude to withstand their blitz of sensory assaults and attempted mind control. All they need is a single moment of weakness and you're dead and/or a willing slave.

Tzeentch can win the battle before it even begins by having implanted cultists slit the throats of your commanders and other key personel the night before, sabotage your cannons or ammo stock, and in general use ♥♥♥♥♥♥♥♥ magic to turn your arms into noodles or some other shenanigans.

Nurgle, you can take limbs off those guys and they'll still come after you, albeit slowly. Get anywhere near them and you'll find your lungs are filling up with maggots, puss, and flies. The stench will be strong enough to empty your bowels, which ironically will probably make it even stronger. If you manage to survive the attack, you'll likely die later due to the cocktail of diseases you are now hosting by getting splashed in the face by whatever juices come out of those pox-walkers.

Honestly, it all sounds like a real bad time pretty equally.

[Ashardalon]

no god can be the strongest for long since tzeentch and chaos itself needs permanent change
so even if tzeentch would be on top he would be weakened if he tried to stay on top
the sneaky manipulative bastard is the referee of the game
but that doesnt make him win because winning would be death
khorne was on top for a long time during empire history tho

slaanesh and nurgle would be a bad time for elves
tzeentch a bad time for humans
and weirdly i think khorne would be the worst time for dwarves