I like them both.
Black ops 2/Halo 4
Graphics:8.3
Storyline: The black ops/treyarch series are ok at making their campaign moments(Modern warfare series is better in my opinon) but the storyline is clear and actually is really good in my opinion. cyber warfare, new weapons, new plot all that stuff.
Multiplayer: New sights and new guns. Awesome killstreaks and great maps. I just love it.(Alot of detail in it, ALOT of gamemodes. Just amazing)
Zombies: In my opinon, tryarch did a great job of improving zombies. I think even better than black ops. THe pack a punch is great. Also new ways on how zombies can appear. SO FUN
Halo 4: Halo always had a good campaign but no offense the campaign is too short. I just wish that Cortana either didn't die or she could have died better. All she said is, Welcome home John. That wasn't very sad... but still, Halo 4 campaign is great and follows up to Halo 3(Which was like the best one yet) It is moving and fun.
Multiplayer. Yes this is great too. Amazing. Really good maps, graphics affect it, some new stuff like a Mantis and new guns! The gamemodes are fun too.(Except for how the shotgun looks like a nerf longshot)
So to conclude, I would give these both game of the year and stop fighting. Dipshit.