Well, I have bought 4 battalions so I had the knights. My thought was people may pay more attention to the krushers and leave the knights to get through.
Heh, well if you have four battalions worth of Knights, I suppose you may as well use them. I really would go for one or the other though; they're not cheap and I find it difficult to rely on cavalry these days when the meta so favours infantry blocks. The steadfast rule makes it much harder for them break units on the charge, after which they get dragged down. Now, Chaos Knights aren't so susceptible to that because they pack a good statline and aren't relying on lances to do get the job done.
For example the tzeentch warriors with the combination of knights and or skullkrushers. I just wanted to make sure they were of a proper hammer/anvil balance or if I need to adjust and use some khorne warriors with halberds as well.
I swear by Khorne Warriors with halberds and sheilds, personally, they hit like a ton of bricks and the shields give them some protection on the way in. Honestly, I've never used Tzeentch Warriors with hand weapons and shields. I can see the logic of using them as an anvil with the cavalry working as the hammer though. Nor have I used the Skullcrushers, so I can't tell you if they're any good or not. They certainly look like a win on paper though.
I do have ALOT of marauders with my 4 battalions as well but do not like the models as well as the chaos warriors and knights.
The models aren't fantastic, but I encourage you to give them a try. For their price, a horde of Marauders with flails and the Mark of Khorne are very good at making a mess of things.