SL / SL forever imo. Takes less skill in a 2v2 you virtually must be this spec, in a 3v3 if its 3 DPS maybe go for something more burst related, but if with a healer you want to out last them so SL / SL again is better. In a 5v5 it can all change slightly i am felguard + shadow burn + instant corruption (can't be bother to link. But this allows me to do lots of damage in a short time of being exposed. My 5v5 is me, MS warrior, Frost mage, Resto druid, Resto Shammy. However i have seen many high rated warlocks as sl /sl in a 5v5 and its good because if they become the focus of attention then they can last for a long time.