I was a huge fan of the cod franchise. MW1, BO, MW2, BO2, and then MW3 is where it started losing me.
I bought ghosts, and hated the multiplayer. The campaign wasn't all that engaging either so I never finished it. Never got AW or IW since the whole mech warrior thing wasn't what I wanted out of a COD game.
I always used to play the campaign fully through before touching the multiplayer, but the newer titles (pretty much anything after BO2) made me totally not want to play the game. The only part of the cod games I still enjoy is doing some splitscreen zombies with friends.