I'll be honest I'm not sure which one's I've specifically played, but I'm pretty sure I've played them all, my GF's brother likes all of the CoD series so I play them whenever I go to her home and I feel like it is the worst map set ups that take no skill to flank so you end up with a never ending shot in the back fest. BF3 takes time and skill to flank, there are areas to sneak behind the lines but they are slow paths and require stealth.
I will say I like CoD:World at War
World at War was by far my favourite too. I have played MW3 for 10 months now, the clan is will hit lv50 this week, we are just under 400 in the world. Its not a realistic game by far, its an arcade shooter really but most play for fun. BF3 was a good game, a better game probably but its the people who make it what it is, I found less teamwork on their, I guess I just prefer the atmosphere of MW3.
Will have to pick up warfighter and see how it plays, like a few other posters I am craving Assassins Creed 3, played them all through and curious to see what happens next. Oh and Dishonored, now that is an awesome game