It depends on your personal tastes and preferences. If you like darker, more serious, somewhat realistic, "darker" shows, then Arrow or Gotham would be more up your alley. If you like more comic book-styled, slightly funny, "brighter" shows, then Flash or Supergirl would be more preferred.
I've seen people on both sides of the coin. If considering Arrow/Flash, though, try watching them both (though you'll have to wait until season 3 of Arrow to do it), because there are a few episodes which crossover.
The Flash for me, but I'm a flash fanboy. I also don't care about Gotham, and I've never watched Supergirl. Really, I'm not the best person to ask.
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.