There are a couple of clear winners when it comes to the new CoKs update IMO. In particular, a few of the faction orders are insane value, at least on paper.
Errata update: While before you were likely to get at least 3 CP every turn, you now start with only 3 red dice, and have to actually invest some points into CP generation if you want to reliably use orders.
Fast units
The two movement orders available to anyone are better the more mobile and nimble your unit is. If you have speed 10 nimble, then those 10″ sidesteps with a pivot can totally change the battle. Alpha striking units also get a big buff in many lists, with +1TC, +1 to hit, elite, pathfinder, strider etc. orders. The ability to remove wavered is also better for nimble and fast units, who can then possibly get away from whoever wavered them, or for chaff, to still be able to do their chaffing duty.
The buff to fast units also means that phalanx increases in value. Most of the quickest units are either fliers, cav or large cav, and a lot have thunderous charge to lose.
This unfortunately also mean that non-phalanx, slow infantry loses a lot of relevance. Infantry heavy armies have always been harder to play IMO, and with an increase in alpha and movement shenanigans, it just got even tougher. Slow infantry is by no means useless, but they need even more support from the rest of the army to be effective.
Dwarfs

One exception to this might be dwarfs. They keep stacking up buffs in every COK, and now, I think they might be at their peak. Rock and Stone is a lunatic order, giving vengeance to any “dwarf” unit, which gives +1CS on counter-charge. Dwarfs have lots of units that are good at not dying, with high def, high nerve, phalanx etc. Getting +1CS on the counter is going to smash a lot of face. Bulwarkers in particular look really good with this order. 30 attacks to get +1CS on, phalanx and def 5+ to survive the charge. With the new order, I think I would skip the shield breaker hordes for bulwarkers. The Royal Guard formation looks especially good with vengeance on the table. 22/24 def 5+ horde, def 5+ phalanx regiments, and they can all hit back on 3+ with native CS1.
With ordered march on pretty much everything, they are also getting a bit more mobile for a slow army. And all their static war engines gain US1. Comparing the dwarf organ gun to the Rhordia volley gun highlights how much better the dwarf ones are. +1US, +1 def, +1 nerve for only +10pts.
Dwarves are already very proficient in slinging high piercing shooting and throwing dogs while surviving the enemy strike to counter. With the new changes, this playing style got even stronger. I do have a retro dwarf army lying around, maybe 2025 will be the year it gets painted? (very few spear-dwarfs in it unfortunately though.) At the same time, the playing style is very reactive / planned, since you have such a slow army, even with ordered march. Some scenarios are very challenging, and terrain is an issue for the army. While I do want to get a lot of “imperial dwarf spearmen” and make an army, I think I will have to test out the playing style to make sure it isn’t too boring.
Errata update: Vengeance now doesn’t work on hordes, a pretty big blow. Dwarves are still good, but seems I was right that they were at their peak, as they just got their first nerf.
Basiliea

My human list will likely move from Rhordia / KoM over to Basiliea (or their slightly worse version, the Brothermark), as they look like a league above in the new power level.
They get one absolutely amazing order in holy assault. Any human or ogre unit can get +1TC on tap. Only angels are kept out of the party here, not like KoM / Rhordia with the big restrictions on their +1 to hit order. And these armies have the units to take advantage. They have decent knight units who love +1TC, they have mini-siegebreakers in Ogre palace guard, they have speed 10 chaff that can suddenly hit TC2 on a flank. In short, they are going to hit hard and get a ton of mileage out of holy assault.
Divine protection is also not limited in use, so you can slap it on Julius and laugh at your opponents puny attempt at killing a living God with Iron resolve 3. I might have to face this in a tourney this weekend, and I am not looking forward to it. Better kill that def 6+ speed 10, nimble, flying -/16 guy in one round…
Speaking of killing in one round… phoenixes. They gained US2 as titans, but I am not actually sure if they gained anything else in COK25, maybe they got cheaper? Whatever the case is, they certainly are absolute beasts. Shooting, mobility, scoring, high nerve, good regen, healing and even a smidge of close combat ability for 145pts. That feels at least 30pts too cheap.
A fun looking infantry unit in Basiliea is the sisterhood infantry. Rampage 10 on a 30 attack unit is pretty wild. Sure, they are def 3+ and only hit on 4+, but they have CS1, vicious and wild charge D3. Probably not an A-level unit, but certainly looks good enough to play. With some bane chant support and the TC order, they will knock out an average of 19 wounds on def 5+ infantry or cavalry.
Sylvan Kin
Stormwind cavalry get a pretty big buff, being able to gain nimble and +1 nerve for just 25 points. That is at least 50% discount for those abilities. To add to that, Sylvan kin can get pathfinder for +15 too, which increases the value of their TC, speed and nimble. These guys are going to just zoom around the board. They can even get ordered march and zip around 18″ with double pivot through terrain. 250pts is very cheap for that kind of wild mobility combined with very good hitting power. It is close to old school drakons IMO, their main weakness being a reliance on TC, and having kind of mediocre access to chaff. I have tried it out, first as a proxy list, and then as an actual army, and I think starting any Sylvan list with 2-3 of those and then go from there is a good plan.

Sylvan kin did pick up a nerf as well, their machine-gun lords with 7-10 attacks at both ranged and melee are no longer available. Still, a shardblade, hunting cat, lord is going to make mince-meat out of most individuals in the game, so elf kings are still playable, they are just not walking around with automatic weaponry any more.
I will play Sylvan kin in a tourney this weekend. I have never played the army I will show up with, but I will make a report on how it goes. I expect the army to do well, but for the general to time out / mess up with my lack of experience π
Errata update: Poor sylvan kin. They were absolutely slaughtered in the errata. The army I played at Kings of Oslo is dead and buried. Now only a single stormwind cav can be upgraded to quicksilver, and it can not be combined with pathfinder. Someone at Mantic doesn’t like the forest elves Apparently that was from an older errata update, which is likely superceeded by COK25, so Sylvan kin should be fine. But please get your shit together Mantic, and delete dead updates from your errata. It is practically impossible to piece together what is the correct rules without companion. Sylvan kin now jumps to loser-position in this update.
Halflings

Another beneficiary of TC+1 order. Halflings also have many units that can use it, and many of those units are pretty cheap. Juggers were already good, and now they are really scary. Wild lancers can suddenly hit like 200pts knight regiments, while costing 150. The sauceror also ended up getting a points reduction, and he was already good. Now he is insane value IMO. Brutal / wild charge D3, TC3, nimble, strider cav coming to a game near you. The aralez with potential 23″ charge is also not a great thing to face. Halflings are kings of buffing their units.
Honorable mentions:

I have a friend who is making a crazy “all skulks” army, and the buffs to skulks take that army from pretty terrible to it suddenly looking fairly playable. Rampage and 24″ giving the normal skulks and the skulk hero decent output for their low points cost. He is easily at well over a hundred shots, and still the entire army is CS1. Still a wild list though.

We’ll see if the upcoming Kings of Oslo tourney changes my mind, or shows me some other winners. There are some armies that I haven’t looked to much at, so might be some others who have gained a lot.
After tourney update: Kings of Oslo results supported much of what is written here. The top 5 armies were 2x Sylvan kin and 3x Basilea, and with battlepoints only, another Basilea. All of those armies had quite a lot of speed. (and a hell of a lot of phoenixes) The rest of the top 10 were 2x riftforged orcs, dwarfs, and undead.

