Halo is a much much much better game although i hate how short it is the content is a lot better than call of duty's and call of duty IS repetitive it is the same game over and over getting worse and worse on each game. . . . .
In call of duty you always have something to do. Reach max level/prestige, camos, gun challenges, kill streaks, nukes, campaign and best of all zombies. You can always have something else to do and have fun doing so. It also has game modes like Infected, AoN and One shot. And I mean come on, zombies. Pretty much a completely different game and it's freaking amazing. When people say it's repetitive it really isn't, it's consistent. One game a year, different developer means refreshing and more stuff to do.
Here is a question for Halo Do you have different stories in the game do you have custom classes in multiplayer, fun zombies mode? I have the answer for that question, NO. Halo only has a few main characters like master chief, but call of duty has so many like Victor Reznov, David Mason, Alex Mason, Captain Price, Soap, Reilly Ghost. And main villains, Raul Menendez, Gaberial Roke, Makorov, Samantha Maxis.