Batman Arkham Origins or Assassins Creed 4

I think both will be great, though I'm personally looking forward to Batman: AO more.

Arkham Origins.

Origins.

AC4 for me.

Since you asked this question on a comic book website (& you have a Nightwing picture), I'd reccomend Batman Arkham Origins for you.

If you like (Batman,) Deathstroke, Black Mask, etc. & a deep story that will involve all these characters with extravagant gameplay along with Batman’s awesome gadgetry and detective skills -> Origins is definitely your choice.

If you’d rather play a game with massive open-world gameplay heavily based on a theme of pirates (and some assassinations -- mind you --), navy ships taking place in a similar era of piracy & you’d like to play as a new assassin with a different origin, I suggest Black Flags.

I personally really dig the massive open-world in AC4 though I don’t like pirates very much which is the reason I won’t be purchasing that game & it feels like just-another-AC game by Ubisoft. There’s no special feel to it. I love the whole story that revolves in Origins with the villains, slightly improved combat system & the live crimes that’ll be taking place in Gotham city, which is why I’d prefer Origins (by a small margin). Though both games are copy-and-paste games from their prequels as they haven’t improved much except with the open-world concepts, their stories, new characters & slightly better graphics. Gameplay-wise though, I'd say AC4 is a bit better due to more freedom.