I'll have to go with CoD, although I am a very avid sports and Fifa fan Call of Duty just seems to do it in the long term for me, so many different options.
Some people's opinions on here seem to be very stale and clearly not thought through, for example, the first comment read something along the lines of "Hmmm the best selling game in the world or a game about soccer?" Unless you haven't noticed 'soccer' , or football as I prefer to call it, Is, if not the most popular, then among the most popular sports in the world? Get you're facts right son.