Editing Warhammer 40,000/7th Edition Tactics/Dark Angels (section)

====Inquisition (Battle Brothers)====

If you don't care about the fluff, why haven't you taken it yet? Seriously, you get 3 Elites Choices (Read: 3 units of Inquisitorial Henchmen) and each of them can take a transport like a Rhino, or a Chimera or a Land Raider or a Valkyrie. 
That makes it worth it right up front, but with the right load out, they can fill holes in your army, so this should be your first choice right here. 
*Inquisitorial Valkyries make up for the Dark Angel's immediate lack of aerial transport options (outside of a Storm Eagle or Caestus Ram) letting you move tactical squads around the tabletop far quicker than in Rhinos.
*Inquisitor detachments can take a Land Raider Prometheus as a dedicated transport, this saves your primary detachment from using up an Elites slot which should be put to best use on Deathwing and Dreadnoughts. Inquisitorial Land Raiders also get Truesilver armour that provides daemon defense and warp stabilisation fields for teleport shenanigans.
*Servo-Skulls and Mystic henchmen work really well alongside Deathwing, but also alongside Drop Pods and Assault Squads. While Ravenwing do get teleport homers, having Inquisitor stuff works on all deep striking units and also give you more table coverage for incoming units, particularly on the first turn for Deathwing Assault.
*Consider taking a Inquisitor in a Valkyrie and a tarpit or two of Acolytes, while still having a full artillery battery from allied guard and doing some screening with large blocks of bolter brothers; or a four lascannon Devastator squad buffed by a psyker Inquisitor with a Conversion Beamer. If there's something your current army is lacking, the Inquisition has something that can compensate for it.