Well what kinda Orks do you run?
CC or Shooty dakka?
Cause in the case of
CC, then you kinda have run the two polar opposite armies. One assault-based army, and one shooty-based army. So to pick something that's different you'd probably need to pick something that lies in between.
Which kinda leaves the Emperor's finest as your best option in that regard. In which case, wait for the Wolves
Also, how many points do you have with your two armies? Cause in my honest opinion, just stick with what you got, and expand on them, so you have options for later games, or the option to play one really big game.