hmm, Kuriotates would be nice, specially since they aren't always the most geared towards a certain religion. We can probably mark off those specifically tied with a religion ... like Hannah the Irin, the shieam leaders, the Khazad leaders, Sabathiel, ect ect ect.
It might be interesting to play as the doviello. Sure many followed Mulcarn at some point, but the Tusk Hillsmen followed Kilmorph even. It would be intersting scenario of the Doviello rebuilding, the dream of a new winter extinquished, looking for a new god to follow behind. Prolly could be a very neutral civ, scared feral men, rather than evil conquerors, although they could always turn to that path again.
I vote for doviello ... or Kurios.