We currently have 19 sith, two of which are GL's. For GAC, I use DR for offense. Much more useful than on defense IMO. I use the typical team with DR, Bast, Malak, HK and Sith Trooper.
Palp and Vader for empire team.
I have been using Talon for my SEE team w/ Sidious, Marauder, and Dooku.
I have the trio with Maul and Savage. May be worth swapping Maul for Talon on this team.
Red Sith Trooper is with FO. That leaves Sith Assassin, but she is only G9.
I don't have LV yet, so I haven't worried about his team. Also don't have Starkiller, which will require a Sith as well.