What is your plan for the army? Stand and shoot? Move and shoot? Assault?
The DW Knights are pretty cool, but you need to think about your delivery system. If you run it as part of a CAD, you can either leave it to the dice when you want to teleport in, but even when it happens, they will be standing around doing a whole lot of nothing (except perhaps drawing fire) for a turn. If you put them into a DW Redemption Force, you can choose before the game starts when you want to teleport in (but you still have the wasted turn); or you can choose on the fly if you take them as part of a DW Strike Force (assuming you also have some Ravenwing; wasted turn still applies). The benefit of taking the DW Knights in a CAD is that you can put them into a Land Raider that they can charge out of and which can give you some shooting while it moves up the table.
I think the DW Command squad is probably better if you are planning on teleporting in because you get to shoot on the turn you arrive. You even get to run and shoot on that turn if you take them as part of the DW Redemption Force or DW Strike Force. However, the former requires a minimum of 2 units of DW Terminators, so you are short a squad with your current list. You are also short an HQ choice for your 1st CAD.
While on the topic of your current list, you are really close to having a Lions Blade Strike Force, which is better than 2 CAD's. All you need to do is swap out one tac squad for an assault squad and take a Chaplain. If you are going the assault route, you might want to swap out the Co. Vets. to fill in the requirements of the formations. For example:
-Chaplain (perhaps w/ Jump pack if you are taking assault marines w/ jump packs)
-5 man Tac Squad x3
Ravenwing Attack Squadron
Now you have the Lion's Blade Strike Force, giving you overwatch at full BS, then you fill it out with:
DW Strike Force
-DW Command Squad
RW Strike Force
-Librarian or Chaplain on Bike
-RW Command Squad
-Something else (Dark Talon? Nephalim Jetfighter? Land Speeder? RW Black Knights?)
You would then have a "Decurion" made up of a Core Formation and an Auxiliary Formation along with 2 other Detachments (RW Strike Force and DW Strike Force) with everything in the "Decurion" firing at full BS on overwatch, with the Ravenwing allowing you to bring in the Deathwing from deep strike reserve whenever you choose, and with the stuff in the RW detachment automatically coming in on Turn 2, moving flat, out, jinking and shooting at full BS on the turn they arrive.