Call of Duty has been like a childhood friend to me. I have been playing these games since the first one came out. These games were always a corner of happiness and boredom-killers for me. Here are some some reasons why I liked these games -
Better Story -
This might come as a controversial topic but still I find myself liking these stories more than any other game. These games have a deep story with a tinge of shocks given in between. If these are made into movies, they would probably be a hit.
Good Character Building -
The story starts of with one character and then continues with many other characters coming in. This makes it more interesting to play the game and understand the story within.
Realistic Weapons -
Latest games from Call of Duty have received many wonderful weapons. Moreover these have a realistic feel in them and even sound like them. Although they aren't shown to be rusty old and shiny new like in Far Cry still they have a numerous attachments and camo which makes them different from others.
Faster Engine -The Quake 3 engine on which all the games have been made is fast and doesn't really disappoint folks with degraded computers or consoles. In developer point of view, these are also quick editable and customizable.
You can read more about it here: Proxgame.com
Other than this there are small factors like the game having tremendous support all over the gamers. Having mods and edits which make the game more interesting and comfortable.