I'm actually getting back into Chaos; I remember *both* the Pete Haines codex and the Gav Thorpe one, and would honestly say I still prefer this one to the previous one. I had skipped out on 6th edition due to professional commitments but am back and gaming since then. Several things I imagine hurt Chaos's image include the following:
Note: I'm not discussing Forgeworld, because IA 13 is a whole different topic in its own right. Likewise, I don't play unbound/generally work within the "2 detachments" restriction of assorted tourneys:
* "Free" Chapter Tactics on Marines: This is a big one. A lot of the complaints/wishlists for Chaos I've come across tend to either revolve around making Marks cheaper/free, or giving "Legion Tactics". Personally, I'm a "your dudes/customizer" type, and found the Chapter Tactics implementation of vanilla marines to be rather ham-fisted. "Ok, they 'count as White Scars'. Ok, they 'count as Raven Guard'." While it's "better" than how 5th ed Marines 'Count as Ultramarines unless you have a Special Character that says otherwise...", I honestly wish that Loyalist Marines were given an updated trait system. That's something for another discussion though; point is, Marines get *more* than Chaos Marines, at initial purchase (I dislike "unit-vs-unit" comparisons, but they're there).
* "Heldrake OP, please nerf": The Marine statline is very common, what with 4 different Loyalist Marine codexes, not to mention Grey Knights and Necrons. Combined with ease of getting cover, and simply deleting units of Marines was unheard of. Then the Heldrake came. It ignored armor. It ignored cover. It ignored firing arcs. It was resilient to anti-aircraft, and could also fly over stuff and wreck it too. Unfortunately, it quickly became a crutch unit, an auto-take. Come 7e, and Heldrakes getting a regular firing arc (they're still deadly, plus they can still hover.)...
For me, I would say the most legitimate complaints are ones of poor army composition. There are a *LOT* of good-to-great units in the army. Even Elites, the weakest section of the list, has its choice of performing units. However, when you put the pieces together, you'll notice the following:
* Your long-range anti-tank is exclusive to your Heavy Support slot. Everything else operates within a 24" range bracket. You "could" run Helbrutes, but you lose out on efficiency. You *could* run Noise Marines, but if they're not blasting infantry...
* Your fast units are either your HQs or your Fast Attack (which have historically competed with heldrakes), or you could sacrifice some of your Heavy Support to add a Maulerfiend. Usually, you'll put your HQ *in* your Fast Attack.
* With the HS and FA slots completely clogged up, you turn to Troops and Elites. If Forgeworld is allowed, rejoice for you have Dreadclaws. If not, you'll see folks run minimal cultist squads (so they can take more toys), or small Marine units with Havoc Rhinos. You won't see: Bikers, infiltrators, transports with long-range anti-tank, or many other things which ease pressure off the FA/HS. A lot of the Elites are basically upscaled Troops, with similar slowness.
So rather than giving Legion Tactics, more Fearless, lots of point adjustments here and there (though I'd enjoy a point break on the Defiler
), if I were asked how to fix Chaos with a simple band-aid fix, I would say the following:
* Move Maulerfiends & Forgefiends to Elites.
This puts *less* pressure on the FA/HS slots and lets you have more freedom in designing your list. And a flexible codex with more build options means you're less predictable ("Gee, an Eldar player. Probably with lots of Wave Serpents, Jetbikes, perhaps a Wraithknight for interdicting units sent to hunt serpents, and perhaps Hawks for objective-grabbing and dismantling knights...").