In summary, if you indulge me by reading this post, I would like to see the chaos cult lists each have an additional core formation choice, or even the elite approach of the BL list. I think, as they are, the lists are difficult to build. I'd propose an iconic formation. For example (and with no bias to the model I like the most), why not have Khorne Daemonic Assault Engines as a core choice, or even the Juggernaughts?
To the point - my list (and why).
I want to take some Lord of Battles - they are Khorne. In fact, I'd suggest they became a core formation choice (though still counted towards the air/titan limit). Experience has shown that a single war engine (especially one without shields) is a bad idea. So I'll take two.
I'd like to take three. However, that's 3x400=1200pts, leaving no points for any fliers - which are the lists only AA (I don't mind that fact, can hurt, but it's alright they only have planes as AA). So far then:
Lord of Battles - 400
Lord of Battles - 400
3 Hellblades - 200
3 Hellblades - 200
Given the core-support restrictions, can we get away with only two retinues? No.
That would be an army with 10 activations (two core, four support, four air/titan), which at 4k points will be massacred. Especially since, as an assault army, the formations will need to double/march up to the enemy who will then plink us into being broken. Not too mention only having 8 ground formations.
So we need three retinues, at 3x325=975pts minimum (we'll upgrade these in a moment). Leaving:
4000 - 1200 - 975 = 1825 for the six support formations (about 300pts each).
Given the points we placed into the Lord of Battles, adding Daemon pools would seem impossible - so we'll not consider them.
The army lacks any 'deep strike' threat. Hellblades are, frankly, useless at attacking AV formations on the back line (deathstrikes, artillery, etc) expecting a single hit (6x AT6+ shots). There are no points left for any Helltalons (and I'm not a big fan of bombers anyway).
So, it would probably be a good idea to add some Terminators - if only to make my opponent weary of teleporting terminators.
However, I've over spent on that formation, and need a 200pt support to balance out. So either Cannons or Armour. Lets pick a Cannon formation, which we can garrison along with one of the retinues (as a foot slogger).
I'm a big fan of the Deamonic Engines (personal bias fully declared), so I want at least two formations of them. However, I have found that the four strong formation is a bit weak (at FSA a few years ago, they keep being broken), so would be tempted to add two defilers to each one - I'd like to add more DEs, but the MW attack on the defiler with infiltrate will be more tactically useful, even if it does slow them down.. so no six strong DE formations
. [As an aside, I'll need to use a DE as a defiler proxy... so it'll still look like six DEs 
]. [Small second aside, who is adding deadnoughts to DE formations? Why is that even an upgrade option?]So we're currently at 3585pts with two support slots left.
Given the 2+ initiative of the LoBs, DE and... well nearly all the formations, and being an assault army, a supreme command is essential (though defiler packs are 1+ initiative... should we take one of them with two DEs instead?). Also, at the moment, we have two BTS formations. Adding a warlord, bumping up one DE formation, we then only have points for one more formation - another set of cannons (no, not predators).
I was tempted to drop one Hellblade and take a Styx. However, I think I'd miss the additional activation in later turns - not to mention the ability to plink a formation on turn 3.
So final list - for comment.
Code:
Retinue + Warlord -- (325+50)=375
Retinue + 4Rhino -- (325+40)=365
Retinue -- 325
Cannon -- 200
Cannon -- 200
Terminator + Daemon Prince -- (400+50)=450
DE+(2xDef) -- (275+65+65)=405
DE+(3xDef) -- (275+65+65+65)=470
Lord of Battles -- 400
Lord of Battles -- 400
3 Hellblades -- 200
3 Hellblades -- 200
Retinue + 4Rhino -- (325+40)=365
Retinue -- 325
Cannon -- 200
Cannon -- 200
Terminator + Daemon Prince -- (400+50)=450
DE+(2xDef) -- (275+65+65)=405
DE+(3xDef) -- (275+65+65+65)=470
Lord of Battles -- 400
Lord of Battles -- 400
3 Hellblades -- 200
3 Hellblades -- 200
3990 points, 12 activations.
The alternative:
Code:
Retinue + Warlord -- (325+50)=375
Retinue + 4Rhino -- (325+40)=365
Retinue -- 325
Cannon -- 200
Cannon -- 200
Terminator + Daemon Prince -- (400+50)=450
DE+(2xDef) -- (275+65+65)=405
DE+(3xDef) -- (275+65+65+65)=470
Lord of Battles -- 400
Lord of Battles -- 400
Lord of Battles -- 400
Retinue + 4Rhino -- (325+40)=365
Retinue -- 325
Cannon -- 200
Cannon -- 200
Terminator + Daemon Prince -- (400+50)=450
DE+(2xDef) -- (275+65+65)=405
DE+(3xDef) -- (275+65+65+65)=470
Lord of Battles -- 400
Lord of Battles -- 400
Lord of Battles -- 400
Would be fun for a one off - not six tournament games in a row... wait, no this isn't for Britcon, ummm.
I'd love to take juggernaughts (because they're another iconic unit) but: a 425pts support choice, no guns (so can't lay blast markers) and a base speed of 20cm (the army is already slow), they need at least one other support formation (retinues also can't lay BMs without upgrades) - does anyone use them?