In most of the games it totally depends on which exclusive Pokemon you want. And it's great if someone you know gets the opposite game you get so you can trade whichever Pokemon you can't get. I haven't played Ruby or Sapphire, but I might get Sapphire since I prefer the Pokemon.
(I got Pokemon Y because I preferred Yveltal over Xerneas).
Personally, I would get Omega Ruby, It also depends if you played one of them before, for example, if you have played Ruby before, that's what I would suggest. Also look at the pokemon specific to the game, like King, I got Pokemon Y because I liked the Mega Charizard more.
I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.