I think Rome has the least to gain. Their economy is in the tank, and have tons of room to expand into. Instead of building several galleys and waging war they could be shoring up their economy and starting to seriously expand.
DMOC/Nakor don't have too much to gain either, except knocking India down a notch or two. I'd say they have the best backstab candidate opportunity within the CoW. Not too much to gain from the war, but imagine the benefits from striking at Dantski or Whosit during the conflict. Whosit mentioning his alliance "Bloc" makes this even smarter. They may be too honorable for this kind of treachery, though.
DMOC/Nakor don't have too much to gain either, except knocking India down a notch or two. I'd say they have the best backstab candidate opportunity within the CoW. Not too much to gain from the war, but imagine the benefits from striking at Dantski or Whosit during the conflict. Whosit mentioning his alliance "Bloc" makes this even smarter. They may be too honorable for this kind of treachery, though.