[Kreuger]

That's practically a blank slate. If you're sticking with slaanesh I'd buy up stuff now. It looks like gw is leaning towards reducing slaanesh's part in 40k as they did in age of Sigmar. I hope they don't but slaanesh is a tough sell for the marketing dept.

You have a bunch of solid pieces in there. Check out the newer daemon engines, the plastic army kits (dark vengeance, betrayal at calth, and the upcoming prospero one.)

 

[Kreuger]

Rhinos are a must in most chaos armies.

Daemon engines are the part of chaos space marines I like the most. They're the only really unique part. Crazy, mutated, baroque, partially living, machines of destruction.

So yes, I mean forge/ mauler fiends. I also mean Heldrakes, defilers, and all the other Forge World ones: blood slaughterers, brass scorpions, Lord of skulls, decimator engines, chaos knight titans, nurgle plague hulk, blight drone, as well as the hell blade/ hell talon fighters.

 

[Kreuger]

Is say stick with what you like. Don't just change "because." I've played mostly khorne and undivided with a smattering of tzeentch, slaanesh, and nurgle for years. Collect what you like!