Welcome to Heresy!
May I suggest Oblits ue to their misinformed nature they make sense with the DG. Also Defilers are a great thing. Lastly Rhinos!!! a little bit of custom work can make them look stellar as well as keeping your army mobile and effective. You can really use everything except raptors (IMO they just dont fit the DG Profile) it just depends on how much converting are you willing to do!