I looked over the various forces and decided that a Gundabad Orc army was for me, these are the ones from the Hobbit trilogy rather than the original films:
Ringwraith of Dol Guldur (Using the Dimerlaik models)
Gundabad Orc Warband with Captain, Swords and Spears
Bolg, Castellan of Mount Gundabad
I have a warband of twelve Hunter Orcs about half painted so will have them up shortly too. This all gives me just over 700pts, and our standard games are 600pts, but i want to add in more of the lower level heroes and another warband of troops to give me more options!