I have never commented your stuff, but with the inclusion of fucktons of your work in the 2.3 patch I want to give my opinion.
Before that, I must say that I know you have spend a lot of time doing these mods, and I congratule you for this hard work.
Chaos
Alpha LegionGreat DLC in general. I like a lot the Chaos Lord cape. Maybe Chaos Terminators need more Alpha Legion simbols. I think there is a bug with Chaos Sorcerer/AC/CSM right shoulder armour, because the "A" and the chains simbols aren't shown.
Black LegionGreat DLC. I specially love the helmet choices (except maybe the Chaos Sorcerer one). Maybe Heretics could have received a bit more love, and the same goes to the Chaos Dread. But since Black Legion is the most "default" Chaos looks
Death Guard.Sorry, but is one of the worst DLC.
- No Chaos Lord changes, when AFAIK exist a Nurgle Chaos Lord (IIRC you used the epic one on the Chaos Terminator).
- No weapon changes, when already exists green effects for Nurgle (PC Plague Sword, for example). In fact, exists a Nurgle Combi bolter and a Nurglish Chaos Lord sword). Simply adding the Nurgle symbol or changing a bit the texture (with a more greeny rotten colour, for example) you could have made the Chainsword/bolters a bit more "nurglish". Or change the boltpistols magazines with the Blighted Bolter one. Or change the default bayonet with a mini GUO sword...
- On CSM/AC there is a colour difference between the shoulders and the rest of the armour. I'm not saying that you could modify the non-shoulders armour pieces with the Plague Marines textures (fuckton of work), but again with a simple change with a more similar colour it would be ok.
The Chaos Terminators and Chaos Dreads models are the best ones. The helmet choices are great too.
I have some Nurglish weapons. I will upload it, so you can take them if you want to improve the Death Guard DLC.
Iron Warriors- Great DLC. I have no complains here. Maybe add that Iron Warriors details on the left side of the Chaos Dread.
Night Lords. Great DLC. The only complain are that maybe the lightings would have been better on the Raptors and not on the CSM, and maybe the shoulders needs too the lightings details. Chaos Terminators could have had more Night Lords details.
Thousands Sons.Good DLC. Same, Chaos Lord could have more details. Personally I will use the Thousans Sons Chaos Dread helmet on the Chaos Lord, and a crest helmet on the Chaos Dread.
World EatersGood DLc. Maybe more details on the weapons, and more skulls and chains. That Chaos Dread was freaking awesome.
Space MarinesBlack TemplarsGood DLc. Maybe a bit more details on Terminators/Dread/ASM, but good in general.
Blood Angels.Not a Blood Angels fanboy, but I like a lot this DLC. My only complains are the Apo and the ASM Sargent models. I prefer a more simple Apo model, more similar to the regular one but with Blood Angels details. They have the Sanguinary Priest, which is the BA Apo.

ASM Sargent could have less details. Weapons could have more Blood Angels details on their weapons.
Imperial Fists.Good DLC. The Tac Sargent chest detail isn't very good, and maybe need more details.
Luna WolvesIt's not bad, but to be a Pre Heresy DLC is very incomplete: Bolters models are too new, Stormbolters instead of Combi Bolters, the Dread... Some of them are very difficult to do (the Dread model), that's true, but other are relatively easy to do. The MK2 model is good, but I think the legs are too big and the shoulders too small. Being the Warmaster Legion, I think the Mk4 would be a more correct model, because they were IIRC the first ones to receive the most recent armours.
Space WolvesGood DLC. Terminators, Scouts, the Apo and Librarian could have more Space Wolves details. Librarian could be more similar to the Rune Priest.
To sum up, in general the DLCs are great, but some of the units/models receive not love at all. Sometimes is understandable (if the unit its "too common" on the fluff) but sometimes not. The Death Guard its the perfect example. They have a very defined aesthetic in armours and weapons. If you don't change it, when already exists ingame a lot of material to work with, makes the result worse, poor worked that it would be.